diff --git a/WordPress-Core/ruleset.xml b/WordPress-Core/ruleset.xml
index bf8b6938d4..ee3bad0504 100644
--- a/WordPress-Core/ruleset.xml
+++ b/WordPress-Core/ruleset.xml
@@ -412,6 +412,29 @@
 	<!-- Covered by the Squiz.Functions.FunctionDeclarationArgumentSpacing.SpacingAfterReference error code. -->
 
 
+	<!--
+	#############################################################################
+	Handbook: Declare Statements, Namespace, and Import Statements - Namespace declarations.
+	Ref: https://developer.wordpress.org/coding-standards/wordpress-coding-standards/php/#namespace-declarations
+	#############################################################################
+	-->
+	<!-- Rule: Each part of a namespace name should consist of capitalized words separated by underscores. -->
+
+	<!-- Rule: Namespace declarations should have exactly one blank line before the declaration and at least one blank line after. -->
+
+	<!-- Covers rule: There should be only one namespace declaration per file... -->
+	<rule ref="Universal.Namespaces.OneDeclarationPerFile"/>
+
+	<!-- Rule: ... and it should be at the top of the file.
+		 Note: with only one namespace declaration, it not being at the top of the file would be a parse error. -->
+
+	<!-- Covers rule: Namespace declarations using curly brace syntax are not allowed. -->
+	<rule ref="Universal.Namespaces.DisallowCurlyBraceSyntax"/>
+
+	<!-- Covers rule: Explicit global namespace declaration (namespace declaration without name) are also not allowed. -->
+	<rule ref="Universal.Namespaces.DisallowDeclarationWithoutName"/>
+
+
 	<!--
 	#############################################################################
 	Handbook: Object-Oriented Programming - Only One Object Structure (Class/Interface/Trait) per File.