diff --git a/packages/core/src/index.ts b/packages/core/src/index.ts
index aef7a3b6ca..7660947c41 100644
--- a/packages/core/src/index.ts
+++ b/packages/core/src/index.ts
@@ -53,6 +53,7 @@ import type { Adapter, AdapterSession, AdapterUser } from "./adapters.js"
 import type {
   Account,
   AuthAction,
+  AuthConfigInternal,
   Awaitable,
   CookiesOptions,
   DefaultSession,
@@ -102,19 +103,22 @@ export async function Auth(
   request: Request,
   config: AuthConfig
 ): Promise<Response | ResponseInternal> {
-  const logger = setLogger(config)
+  const configWithLogger: AuthConfigInternal = {
+    ...config,
+    logger: setLogger(config),
+  }
 
-  const internalRequest = await toInternalRequest(request, config)
+  const internalRequest = await toInternalRequest(request, configWithLogger)
   // There was an error parsing the request
   if (!internalRequest) return Response.json(`Bad request.`, { status: 400 })
 
   const warningsOrError = assertConfig(internalRequest, config)
 
   if (Array.isArray(warningsOrError)) {
-    warningsOrError.forEach(logger.warn)
+    warningsOrError.forEach(configWithLogger.logger.warn)
   } else if (warningsOrError) {
     // If there's an error in the user config, bail out early
-    logger.error(warningsOrError)
+    configWithLogger.logger.error(warningsOrError)
     const htmlPages = new Set<AuthAction>([
       "signin",
       "signout",
@@ -143,7 +147,7 @@ export async function Auth(
     // Either there was no error page configured or the configured one contains infinite redirects
     if (!pages?.error || authOnErrorPage) {
       if (authOnErrorPage) {
-        logger.error(
+        configWithLogger.logger.error(
           new ErrorPageLoop(
             `The error page ${pages?.error} should not require authentication`
           )
@@ -161,7 +165,10 @@ export async function Auth(
   const isRedirect = request.headers?.has("X-Auth-Return-Redirect")
   const isRaw = config.raw === raw
   try {
-    const internalResponse = await AuthInternal(internalRequest, config)
+    const internalResponse = await AuthInternal(
+      internalRequest,
+      configWithLogger
+    )
     if (isRaw) return internalResponse
 
     const response = toResponse(internalResponse)
@@ -172,7 +179,7 @@ export async function Auth(
     return Response.json({ url }, { headers: response.headers })
   } catch (e) {
     const error = e as Error
-    logger.error(error)
+    configWithLogger.logger.error(error)
 
     const isAuthError = error instanceof AuthError
     if (isAuthError && isRaw && !isRedirect) throw error
diff --git a/packages/core/src/lib/index.ts b/packages/core/src/lib/index.ts
index 00ee0027c1..937e98d6f3 100644
--- a/packages/core/src/lib/index.ts
+++ b/packages/core/src/lib/index.ts
@@ -4,9 +4,11 @@ import { init } from "./init.js"
 import renderPage from "./pages/index.js"
 import * as actions from "./actions/index.js"
 import { validateCSRF } from "./actions/callback/oauth/csrf-token.js"
-
-import type { RequestInternal, ResponseInternal } from "../types.js"
-import type { AuthConfig } from "../index.js"
+import type {
+  AuthConfigInternal,
+  RequestInternal,
+  ResponseInternal,
+} from "../types.js"
 import { skipCSRFCheck } from "./symbols.js"
 
 export { customFetch, raw, skipCSRFCheck } from "./symbols.js"
@@ -14,7 +16,7 @@ export { customFetch, raw, skipCSRFCheck } from "./symbols.js"
 /** @internal */
 export async function AuthInternal(
   request: RequestInternal,
-  authOptions: AuthConfig
+  authOptions: AuthConfigInternal
 ): Promise<ResponseInternal> {
   const { action, providerId, error, method } = request
 
diff --git a/packages/core/src/lib/init.ts b/packages/core/src/lib/init.ts
index 9e8ca122f6..d61272919a 100644
--- a/packages/core/src/lib/init.ts
+++ b/packages/core/src/lib/init.ts
@@ -5,15 +5,19 @@ import { createCSRFToken } from "./actions/callback/oauth/csrf-token.js"
 
 import { AdapterError, EventError } from "../errors.js"
 import parseProviders from "./utils/providers.js"
-import { setLogger, type LoggerInstance } from "./utils/logger.js"
+import type { LoggerInstance } from "./utils/logger.js"
 import { merge } from "./utils/merge.js"
 
-import type { InternalOptions, RequestInternal } from "../types.js"
+import type {
+  AuthConfigInternal,
+  InternalOptions,
+  RequestInternal,
+} from "../types.js"
 import type { AuthConfig } from "../index.js"
 
 interface InitParams {
   url: URL
-  authOptions: AuthConfig
+  authOptions: AuthConfigInternal
   providerId?: string
   action: InternalOptions["action"]
   /** Callback URL value extracted from the incoming request. */
@@ -65,7 +69,6 @@ export async function init({
   options: InternalOptions
   cookies: cookie.Cookie[]
 }> {
-  const logger = setLogger(config)
   const { providers, provider } = parseProviders({ url, providerId, config })
 
   const maxAge = 30 * 24 * 60 * 60 // Sessions expire after 30 days of being idle by default
@@ -129,11 +132,11 @@ export async function init({
       ...config.jwt,
     },
     // Event messages
-    events: eventsErrorHandler(config.events ?? {}, logger),
-    adapter: adapterErrorHandler(config.adapter, logger),
+    events: eventsErrorHandler(config.events ?? {}, config.logger),
+    adapter: adapterErrorHandler(config.adapter, config.logger),
     // Callback functions
     callbacks: { ...defaultCallbacks, ...config.callbacks },
-    logger,
+    logger: config.logger,
     callbackUrl: url.origin,
     isOnRedirectProxy,
     experimental: {
diff --git a/packages/core/src/lib/utils/logger.ts b/packages/core/src/lib/utils/logger.ts
index e9e5c85858..9941318eef 100644
--- a/packages/core/src/lib/utils/logger.ts
+++ b/packages/core/src/lib/utils/logger.ts
@@ -63,12 +63,13 @@ export function setLogger(
     ...defaultLogger,
   }
 
-  // Turn off debug logging if `debug` isn't set to `true`
-  if (!config.debug) newLogger.debug = () => {}
-
   if (config.logger?.error) newLogger.error = config.logger.error
   if (config.logger?.warn) newLogger.warn = config.logger.warn
-  if (config.logger?.debug) newLogger.debug = config.logger.debug
+
+  // Disable debug logging if `debug` is not explicitly set to `true`, even if a custom logger is provided
+  if (!config.debug) newLogger.debug = () => {}
+  if (config.debug && config.logger?.debug)
+    newLogger.debug = config.logger.debug
 
   config.logger ??= newLogger
   return newLogger
diff --git a/packages/core/src/lib/utils/web.ts b/packages/core/src/lib/utils/web.ts
index fdbafbcadc..8c4a036b2c 100644
--- a/packages/core/src/lib/utils/web.ts
+++ b/packages/core/src/lib/utils/web.ts
@@ -1,14 +1,12 @@
 import * as cookie from "../vendored/cookie.js"
 import { UnknownAction } from "../../errors.js"
-import { setLogger } from "./logger.js"
-
 import type {
   AuthAction,
+  AuthConfigInternal,
   RequestInternal,
   ResponseInternal,
 } from "../../types.js"
 import { isAuthAction } from "./actions.js"
-import type { AuthConfig } from "../../index.js"
 
 const { parse: parseCookie, serialize: serializeCookie } = cookie
 
@@ -26,7 +24,7 @@ async function getBody(req: Request): Promise<Record<string, any> | undefined> {
 
 export async function toInternalRequest(
   req: Request,
-  config: AuthConfig
+  config: AuthConfigInternal
 ): Promise<RequestInternal | undefined> {
   try {
     if (req.method !== "GET" && req.method !== "POST")
@@ -54,9 +52,8 @@ export async function toInternalRequest(
       query: Object.fromEntries(url.searchParams),
     }
   } catch (e) {
-    const logger = setLogger(config)
-    logger.error(e as Error)
-    logger.debug("request", req)
+    config.logger.error(e as Error)
+    config.logger.debug("request", req)
   }
 }
 
diff --git a/packages/core/src/types.ts b/packages/core/src/types.ts
index b6653ffe04..1b91325312 100644
--- a/packages/core/src/types.ts
+++ b/packages/core/src/types.ts
@@ -428,3 +428,7 @@ export interface InternalOptions<TProviderType = ProviderType> {
   experimental: NonNullable<AuthConfig["experimental"]>
   basePath: string
 }
+
+export type AuthConfigInternal = Omit<AuthConfig, "logger"> & {
+  logger: LoggerInstance
+}
diff --git a/packages/core/test/logger.test.ts b/packages/core/test/logger.test.ts
new file mode 100644
index 0000000000..198aad23af
--- /dev/null
+++ b/packages/core/test/logger.test.ts
@@ -0,0 +1,56 @@
+import { describe, it, expect, vi } from "vitest"
+import { setLogger } from "../src/lib/utils/logger"
+import type { AuthConfig } from "../src/types.ts"
+
+describe("setLogger", () => {
+  it("should return default logger if no custom logger is provided", () => {
+    const logger = setLogger({})
+    expect(logger.error).toBeInstanceOf(Function)
+    expect(logger.debug).toBeInstanceOf(Function)
+    expect(logger.warn).toBeInstanceOf(Function)
+  })
+
+  it("should override error and warn with custom logger", () => {
+    const customError = vi.fn()
+    const customWarn = vi.fn()
+    const logger = setLogger({
+      logger: {
+        error: customError,
+        warn: customWarn,
+      },
+    })
+    expect(logger.error).toBe(customError)
+    expect(logger.warn).toBe(customWarn)
+    expect(logger.debug).toBeInstanceOf(Function)
+  })
+
+  it("should override debug only if debug is true", () => {
+    const customDebug = vi.fn()
+    const logger1 = setLogger({
+      logger: {
+        debug: customDebug,
+      },
+      debug: true,
+    })
+    expect(logger1.debug).toBe(customDebug)
+    expect(logger1.error).toBeInstanceOf(Function)
+    expect(logger1.warn).toBeInstanceOf(Function)
+
+    const logger2 = setLogger({
+      logger: {
+        debug: customDebug,
+      },
+      debug: false,
+    })
+    expect(logger2.debug).not.toBe(customDebug)
+    expect(logger2.debug).toBeInstanceOf(Function)
+    expect(logger2.error).toBeInstanceOf(Function)
+    expect(logger2.warn).toBeInstanceOf(Function)
+  })
+
+  it("should assign the new logger to config.logger if not present", () => {
+    const config: Partial<AuthConfig> = {}
+    const logger = setLogger(config)
+    expect(config.logger).toBe(logger)
+  })
+})