diff --git a/packages/types/src/global-settings.ts b/packages/types/src/global-settings.ts
index 3b80bba3b2..897cffb9e7 100644
--- a/packages/types/src/global-settings.ts
+++ b/packages/types/src/global-settings.ts
@@ -148,6 +148,12 @@ export const globalSettingsSchema = z.object({
 	hasOpenedModeSelector: z.boolean().optional(),
 	lastModeExportPath: z.string().optional(),
 	lastModeImportPath: z.string().optional(),
+
+	/**
+	 * Custom instruction file paths, directories, or glob patterns.
+	 * Supports single files, directories, glob patterns, and parent directory paths.
+	 */
+	customInstructionPaths: z.array(z.string()).optional(),
 })
 
 export type GlobalSettings = z.infer<typeof globalSettingsSchema>
diff --git a/src/core/prompts/sections/__tests__/custom-instructions.test.ts b/src/core/prompts/sections/__tests__/custom-instructions.test.ts
new file mode 100644
index 0000000000..c68cf4becf
--- /dev/null
+++ b/src/core/prompts/sections/__tests__/custom-instructions.test.ts
@@ -0,0 +1,341 @@
+import { describe, it, expect, vi, beforeEach } from "vitest"
+import * as path from "path"
+
+// Mock modules before importing the function to test
+vi.mock("fs/promises", () => ({
+	default: {},
+	stat: vi.fn(),
+	readFile: vi.fn(),
+	readdir: vi.fn(),
+}))
+
+vi.mock("glob", () => ({
+	glob: vi.fn().mockResolvedValue([]),
+}))
+
+// Import after mocking
+import { loadCustomInstructionFiles } from "../custom-instructions"
+import * as fs from "fs/promises"
+import { glob } from "glob"
+
+describe("loadCustomInstructionFiles", () => {
+	const mockCwd = "/workspace/project"
+
+	beforeEach(() => {
+		vi.clearAllMocks()
+		// Reset console.warn mock
+		vi.spyOn(console, "warn").mockImplementation(() => {})
+	})
+
+	describe("basic functionality", () => {
+		it("should return empty string when customPaths is undefined", async () => {
+			const result = await loadCustomInstructionFiles(mockCwd, undefined)
+			expect(result).toBe("")
+		})
+
+		it("should return empty string when customPaths is empty array", async () => {
+			const result = await loadCustomInstructionFiles(mockCwd, [])
+			expect(result).toBe("")
+		})
+	})
+
+	describe("single file loading", () => {
+		it("should load content from a single file", async () => {
+			const filePath = ".github/copilot-instructions.md"
+			const resolvedPath = path.resolve(mockCwd, filePath)
+			const mockContent = "Custom Instructions"
+
+			// Setup mocks
+			vi.mocked(fs.stat).mockResolvedValue({
+				isFile: () => true,
+				isDirectory: () => false,
+				size: 100,
+			} as any)
+
+			vi.mocked(fs.readFile).mockResolvedValue(mockContent)
+
+			const result = await loadCustomInstructionFiles(mockCwd, [filePath])
+
+			expect(fs.stat).toHaveBeenCalledWith(resolvedPath)
+			expect(fs.readFile).toHaveBeenCalledWith(resolvedPath, "utf-8")
+			expect(result).toContain("Custom Instructions")
+			expect(result).toContain(`# Custom instructions from ${filePath}:`)
+		})
+
+		it("should skip files that exceed size limit", async () => {
+			vi.mocked(fs.stat).mockResolvedValue({
+				isFile: () => true,
+				isDirectory: () => false,
+				size: 2 * 1024 * 1024, // 2MB
+			} as any)
+
+			const result = await loadCustomInstructionFiles(mockCwd, ["large-file.md"])
+
+			expect(fs.readFile).not.toHaveBeenCalled()
+			expect(result).toBe("")
+		})
+
+		it("should skip files without allowed extensions", async () => {
+			vi.mocked(fs.stat).mockResolvedValue({
+				isFile: () => true,
+				isDirectory: () => false,
+				size: 100,
+			} as any)
+
+			const result = await loadCustomInstructionFiles(mockCwd, ["file.js"])
+
+			expect(fs.readFile).not.toHaveBeenCalled()
+			expect(result).toBe("")
+		})
+	})
+
+	describe("directory loading", () => {
+		it("should load all .md and .txt files from a directory", async () => {
+			const dirPath = ".roocode"
+			const resolvedPath = path.resolve(mockCwd, dirPath)
+
+			// Mock stat to identify as directory
+			vi.mocked(fs.stat)
+				.mockResolvedValueOnce({
+					isFile: () => false,
+					isDirectory: () => true,
+				} as any)
+				// For individual files
+				.mockResolvedValue({
+					isFile: () => true,
+					isDirectory: () => false,
+					size: 100,
+				} as any)
+
+			// Mock readdir
+			vi.mocked(fs.readdir).mockResolvedValue([
+				{ name: "instructions.md", isFile: () => true, isDirectory: () => false },
+				{ name: "rules.txt", isFile: () => true, isDirectory: () => false },
+				{ name: "image.png", isFile: () => true, isDirectory: () => false },
+			] as any)
+
+			// Mock readFile
+			vi.mocked(fs.readFile).mockResolvedValueOnce("Instructions content").mockResolvedValueOnce("Rules content")
+
+			const result = await loadCustomInstructionFiles(mockCwd, [dirPath])
+
+			expect(fs.readdir).toHaveBeenCalledWith(resolvedPath, { withFileTypes: true })
+			expect(fs.readFile).toHaveBeenCalledTimes(2) // Only .md and .txt files
+			expect(result).toContain("Instructions content")
+			expect(result).toContain("Rules content")
+		})
+	})
+
+	describe("glob patterns", () => {
+		it("should expand glob patterns and load matching files", async () => {
+			const pattern = "docs/**/*.md"
+			const matches = [path.resolve(mockCwd, "docs/api.md"), path.resolve(mockCwd, "docs/guide.md")]
+
+			// Mock stat to fail first (triggering glob)
+			vi.mocked(fs.stat)
+				.mockRejectedValueOnce(new Error("Not found"))
+				.mockResolvedValue({
+					isFile: () => true,
+					isDirectory: () => false,
+					size: 100,
+				} as any)
+
+			// Mock glob
+			vi.mocked(glob).mockResolvedValue(matches)
+
+			// Mock readFile
+			vi.mocked(fs.readFile).mockResolvedValueOnce("API docs").mockResolvedValueOnce("Guide docs")
+
+			const result = await loadCustomInstructionFiles(mockCwd, [pattern])
+
+			expect(glob).toHaveBeenCalledWith(pattern, {
+				cwd: mockCwd,
+				absolute: true,
+				nodir: true,
+				ignore: ["**/node_modules/**", "**/.git/**"],
+			})
+			expect(result).toContain("API docs")
+			expect(result).toContain("Guide docs")
+		})
+	})
+
+	describe("security validation", () => {
+		it("should reject paths outside workspace and parent", async () => {
+			const outsidePath = "/etc/passwd"
+
+			vi.mocked(fs.stat).mockResolvedValue({
+				isFile: () => true,
+				isDirectory: () => false,
+				size: 50,
+			} as any)
+
+			const result = await loadCustomInstructionFiles(mockCwd, [outsidePath])
+
+			expect(fs.readFile).not.toHaveBeenCalled()
+			expect(console.warn).toHaveBeenCalledWith(
+				expect.stringContaining("Skipping instruction path outside allowed directories"),
+			)
+			expect(result).toBe("")
+		})
+
+		it("should allow parent directory access", async () => {
+			const parentPath = "../parent-instructions.md"
+			// This resolves to /workspace/parent-instructions.md which is in the parent dir
+			const resolvedPath = "/workspace/parent-instructions.md"
+
+			vi.mocked(fs.stat).mockResolvedValue({
+				isFile: () => true,
+				isDirectory: () => false,
+				size: 50,
+			} as any)
+
+			vi.mocked(fs.readFile).mockResolvedValue("Parent instructions")
+
+			const result = await loadCustomInstructionFiles(mockCwd, [parentPath])
+
+			expect(result).toContain("Parent instructions")
+			expect(result).toContain("# Custom instructions from ../parent-instructions.md:")
+		})
+
+		it("should allow workspace subdirectories", async () => {
+			const subPath = "src/rules/custom.md"
+
+			vi.mocked(fs.stat).mockResolvedValue({
+				isFile: () => true,
+				isDirectory: () => false,
+				size: 50,
+			} as any)
+
+			vi.mocked(fs.readFile).mockResolvedValue("Subdirectory content")
+
+			const result = await loadCustomInstructionFiles(mockCwd, [subPath])
+
+			expect(result).toContain("Subdirectory content")
+			expect(result).toContain("# Custom instructions from src/rules/custom.md:")
+		})
+	})
+
+	describe("error handling", () => {
+		it("should handle file read errors gracefully", async () => {
+			vi.mocked(fs.stat).mockResolvedValue({
+				isFile: () => true,
+				isDirectory: () => false,
+				size: 100,
+			} as any)
+
+			vi.mocked(fs.readFile).mockRejectedValue(new Error("Permission denied"))
+
+			const result = await loadCustomInstructionFiles(mockCwd, ["protected.md"])
+
+			expect(console.warn).toHaveBeenCalledWith(
+				expect.stringContaining("Error reading instruction file"),
+				expect.any(Error),
+			)
+			expect(result).toBe("")
+		})
+
+		it("should handle glob errors gracefully", async () => {
+			vi.mocked(fs.stat).mockRejectedValue(new Error("Not found"))
+
+			vi.mocked(glob).mockRejectedValue(new Error("Invalid pattern"))
+
+			const result = await loadCustomInstructionFiles(mockCwd, ["[invalid"])
+
+			expect(console.warn).toHaveBeenCalledWith(
+				expect.stringContaining("Error processing custom instruction path"),
+				expect.any(Error),
+			)
+			expect(result).toBe("")
+		})
+
+		it("should handle directory read errors gracefully", async () => {
+			vi.mocked(fs.stat).mockResolvedValue({
+				isFile: () => false,
+				isDirectory: () => true,
+			} as any)
+
+			vi.mocked(fs.readdir).mockRejectedValue(new Error("Permission denied"))
+
+			const result = await loadCustomInstructionFiles(mockCwd, [".roocode"])
+
+			// Should fall through to glob attempt
+			expect(result).toBe("")
+		})
+	})
+
+	describe("content formatting", () => {
+		it("should format content with proper headers", async () => {
+			vi.mocked(fs.stat).mockResolvedValue({
+				isFile: () => true,
+				isDirectory: () => false,
+				size: 50,
+			} as any)
+			vi.mocked(fs.readFile).mockResolvedValue("Test content")
+
+			const result = await loadCustomInstructionFiles(mockCwd, ["test.md"])
+
+			expect(result).toContain("# Custom instructions from test.md:")
+			expect(result).toContain("Test content")
+		})
+
+		it("should combine multiple files with proper formatting", async () => {
+			vi.mocked(fs.stat).mockResolvedValue({
+				isFile: () => true,
+				isDirectory: () => false,
+				size: 50,
+			} as any)
+			vi.mocked(fs.readFile).mockResolvedValueOnce("Content 1").mockResolvedValueOnce("Content 2")
+
+			const result = await loadCustomInstructionFiles(mockCwd, ["file1.md", "file2.md"])
+
+			expect(result).toMatch(
+				/# Custom instructions from file1\.md:[\s\S]*Content 1[\s\S]*# Custom instructions from file2\.md:[\s\S]*Content 2/,
+			)
+		})
+	})
+
+	describe("mixed path types", () => {
+		it("should handle a mix of files, directories, and globs", async () => {
+			// Setup for single file
+			vi.mocked(fs.stat)
+				.mockResolvedValueOnce({
+					isFile: () => true,
+					isDirectory: () => false,
+					size: 50,
+				} as any)
+				// Setup for directory
+				.mockResolvedValueOnce({
+					isFile: () => false,
+					isDirectory: () => true,
+				} as any)
+				// Setup for glob (will fail stat, triggering glob)
+				.mockRejectedValueOnce(new Error("Not found"))
+				// For directory file and glob file
+				.mockResolvedValue({
+					isFile: () => true,
+					isDirectory: () => false,
+					size: 50,
+				} as any)
+
+			// Setup directory listing
+			vi.mocked(fs.readdir).mockResolvedValue([
+				{ name: "dir-file.md", isFile: () => true, isDirectory: () => false },
+			] as any)
+
+			// Setup glob
+			vi.mocked(glob).mockResolvedValue([path.resolve(mockCwd, "docs/glob-file.md")])
+
+			// Setup file reads
+			vi.mocked(fs.readFile)
+				.mockResolvedValueOnce("Single file content")
+				.mockResolvedValueOnce("Directory file content")
+				.mockResolvedValueOnce("Glob file content")
+
+			const result = await loadCustomInstructionFiles(mockCwd, ["single.md", ".roocode", "docs/**/*.md"])
+
+			expect(result).toContain("Single file content")
+			expect(result).toContain("Directory file content")
+			expect(result).toContain("Glob file content")
+		})
+	})
+})
diff --git a/src/core/prompts/sections/custom-instructions.ts b/src/core/prompts/sections/custom-instructions.ts
index 2d70e45419..c3dd7ae363 100644
--- a/src/core/prompts/sections/custom-instructions.ts
+++ b/src/core/prompts/sections/custom-instructions.ts
@@ -2,6 +2,7 @@ import fs from "fs/promises"
 import path from "path"
 import * as os from "os"
 import { Dirent } from "fs"
+import { glob } from "glob"
 
 import { isLanguage } from "@roo-code/types"
 
@@ -261,6 +262,128 @@ async function loadAgentRulesFile(cwd: string): Promise<string> {
 	return ""
 }
 
+/**
+ * Load custom instruction files from specified paths, directories, or glob patterns
+ * @param cwd Current working directory for resolving relative paths
+ * @param customPaths Array of paths, directories, or glob patterns
+ * @returns Combined content from all loaded instruction files
+ */
+export async function loadCustomInstructionFiles(cwd: string, customPaths?: string[]): Promise<string> {
+	if (!customPaths || customPaths.length === 0) {
+		return ""
+	}
+
+	const loadedFiles: Array<{ path: string; content: string }> = []
+	const MAX_FILE_SIZE = 1024 * 1024 // 1MB limit per file
+	const ALLOWED_EXTENSIONS = [".md", ".markdown", ".txt"]
+
+	for (const pathPattern of customPaths) {
+		try {
+			// Resolve the path relative to the workspace
+			const resolvedPath = path.isAbsolute(pathPattern) ? pathPattern : path.resolve(cwd, pathPattern)
+
+			// Security validation: ensure path is within workspace or parent directories
+			const normalizedPath = path.normalize(resolvedPath)
+			const normalizedCwd = path.normalize(cwd)
+			const parentDir = path.dirname(normalizedCwd)
+
+			// Allow files within workspace or one level up (for monorepo scenarios)
+			if (!normalizedPath.startsWith(normalizedCwd) && !normalizedPath.startsWith(parentDir)) {
+				console.warn(`Skipping instruction path outside allowed directories: ${pathPattern}`)
+				continue
+			}
+
+			// Check if it's a directory
+			try {
+				const stats = await fs.stat(resolvedPath)
+				if (stats.isDirectory()) {
+					// Load all markdown and text files from the directory
+					const dirFiles = await fs.readdir(resolvedPath, { withFileTypes: true })
+					for (const file of dirFiles) {
+						if (file.isFile()) {
+							const ext = path.extname(file.name).toLowerCase()
+							if (ALLOWED_EXTENSIONS.includes(ext)) {
+								const filePath = path.join(resolvedPath, file.name)
+								const content = await loadSingleFile(filePath, MAX_FILE_SIZE)
+								if (content) {
+									loadedFiles.push({ path: filePath, content })
+								}
+							}
+						}
+					}
+					continue
+				} else if (stats.isFile()) {
+					// It's a single file
+					const ext = path.extname(resolvedPath).toLowerCase()
+					if (ALLOWED_EXTENSIONS.includes(ext)) {
+						const content = await loadSingleFile(resolvedPath, MAX_FILE_SIZE)
+						if (content) {
+							loadedFiles.push({ path: resolvedPath, content })
+						}
+					}
+					continue
+				}
+			} catch (err) {
+				// File/directory doesn't exist, might be a glob pattern
+			}
+
+			// Try as a glob pattern
+			const matches = await glob(pathPattern, {
+				cwd: cwd,
+				absolute: true,
+				nodir: true,
+				ignore: ["**/node_modules/**", "**/.git/**"],
+			})
+
+			for (const matchedFile of matches) {
+				const ext = path.extname(matchedFile).toLowerCase()
+				if (ALLOWED_EXTENSIONS.includes(ext)) {
+					// Apply same security validation
+					const normalizedMatch = path.normalize(matchedFile)
+					if (!normalizedMatch.startsWith(normalizedCwd) && !normalizedMatch.startsWith(parentDir)) {
+						console.warn(`Skipping matched file outside allowed directories: ${matchedFile}`)
+						continue
+					}
+
+					const content = await loadSingleFile(matchedFile, MAX_FILE_SIZE)
+					if (content) {
+						loadedFiles.push({ path: matchedFile, content })
+					}
+				}
+			}
+		} catch (error) {
+			console.warn(`Error processing custom instruction path "${pathPattern}":`, error)
+		}
+	}
+
+	// Combine all loaded content with file headers
+	if (loadedFiles.length === 0) {
+		return ""
+	}
+
+	return loadedFiles
+		.map((file) => `# Custom instructions from ${path.relative(cwd, file.path)}:\n${file.content}`)
+		.join("\n\n")
+}
+
+/**
+ * Load a single file with size validation
+ */
+async function loadSingleFile(filePath: string, maxSize: number): Promise<string | null> {
+	try {
+		const stats = await fs.stat(filePath)
+		if (stats.size > maxSize) {
+			console.warn(`Skipping large instruction file (>${maxSize} bytes): ${filePath}`)
+			return null
+		}
+		const content = await fs.readFile(filePath, "utf-8")
+		return content.trim()
+	} catch (error) {
+		console.warn(`Error reading instruction file "${filePath}":`, error)
+		return null
+	}
+}
+
 export async function addCustomInstructions(
 	modeCustomInstructions: string,
 	globalCustomInstructions: string,
@@ -270,6 +393,7 @@ export async function addCustomInstructions(
 		language?: string
 		rooIgnoreInstructions?: string
 		settings?: SystemPromptSettings
+		customInstructionPaths?: string[]
 	} = {},
 ): Promise<string> {
 	const sections = []
@@ -366,6 +490,14 @@ export async function addCustomInstructions(
 		sections.push(`Rules:\n\n${rules.join("\n\n")}`)
 	}
 
+	// Load custom instruction files from paths
+	if (options.customInstructionPaths && options.customInstructionPaths.length > 0) {
+		const customFileContent = await loadCustomInstructionFiles(cwd, options.customInstructionPaths)
+		if (customFileContent && customFileContent.trim()) {
+			sections.push(`Custom Instruction Files:\n\n${customFileContent.trim()}`)
+		}
+	}
+
 	const joinedSections = sections.join("\n\n")
 
 	return joinedSections
diff --git a/src/core/prompts/system.ts b/src/core/prompts/system.ts
index 3cc327c815..081520cd2f 100644
--- a/src/core/prompts/system.ts
+++ b/src/core/prompts/system.ts
@@ -62,6 +62,7 @@ async function generatePrompt(
 	settings?: SystemPromptSettings,
 	todoList?: TodoItem[],
 	modelId?: string,
+	customInstructionPaths?: string[],
 ): Promise<string> {
 	if (!context) {
 		throw new Error("Extension context is required for generating system prompt")
@@ -128,6 +129,7 @@ ${await addCustomInstructions(baseInstructions, globalCustomInstructions || "",
 	language: language ?? formatLanguage(vscode.env.language),
 	rooIgnoreInstructions,
 	settings,
+	customInstructionPaths,
 })}`
 
 	return basePrompt
@@ -153,6 +155,7 @@ export const SYSTEM_PROMPT = async (
 	settings?: SystemPromptSettings,
 	todoList?: TodoItem[],
 	modelId?: string,
+	customInstructionPaths?: string[],
 ): Promise<string> => {
 	if (!context) {
 		throw new Error("Extension context is required for generating system prompt")
@@ -191,6 +194,7 @@ export const SYSTEM_PROMPT = async (
 				language: language ?? formatLanguage(vscode.env.language),
 				rooIgnoreInstructions,
 				settings,
+				customInstructionPaths,
 			},
 		)
 
@@ -225,5 +229,6 @@ ${customInstructions}`
 		settings,
 		todoList,
 		modelId,
+		customInstructionPaths,
 	)
 }
diff --git a/src/core/task/Task.ts b/src/core/task/Task.ts
index 104cb87206..ed6a8a95ed 100644
--- a/src/core/task/Task.ts
+++ b/src/core/task/Task.ts
@@ -2196,6 +2196,7 @@ export class Task extends EventEmitter<TaskEvents> implements TaskLike {
 			customModes,
 			customModePrompts,
 			customInstructions,
+			customInstructionPaths,
 			experiments,
 			enableMcpServerCreation,
 			browserToolEnabled,
@@ -2239,6 +2240,7 @@ export class Task extends EventEmitter<TaskEvents> implements TaskLike {
 				},
 				undefined, // todoList
 				this.api.getModel().id,
+				customInstructionPaths,
 			)
 		})()
 	}
diff --git a/src/core/webview/ClineProvider.ts b/src/core/webview/ClineProvider.ts
index 18fa70035b..04b84285af 100644
--- a/src/core/webview/ClineProvider.ts
+++ b/src/core/webview/ClineProvider.ts
@@ -1974,6 +1974,7 @@ export class ClineProvider
 			apiConfiguration: providerSettings,
 			lastShownAnnouncementId: stateValues.lastShownAnnouncementId,
 			customInstructions: stateValues.customInstructions,
+			customInstructionPaths: stateValues.customInstructionPaths,
 			apiModelId: stateValues.apiModelId,
 			alwaysAllowReadOnly: stateValues.alwaysAllowReadOnly ?? false,
 			alwaysAllowReadOnlyOutsideWorkspace: stateValues.alwaysAllowReadOnlyOutsideWorkspace ?? false,