diff --git a/.github/files/lint-project-structure.sh b/.github/files/lint-project-structure.sh
index f081abc47b41c..923455db849c6 100755
--- a/.github/files/lint-project-structure.sh
+++ b/.github/files/lint-project-structure.sh
@@ -642,6 +642,11 @@ if ! pnpm semver --range "$RANGE" "$PNPM_VERSION" &>/dev/null; then
 	LINE=$(jq --stream 'if length == 1 then .[0][:-1] else .[0] end | if . == ["engines","pnpm"] then input_line_number - 1 else empty end' package.json)
 	echo "::error file=package.json,line=$LINE::Pnpm version $PNPM_VERSION in .github/versions.sh does not satisfy requirement $RANGE from package.json"
 fi
+if ! jq -e --arg v "pnpm@$PNPM_VERSION" '.packageManager == $v' package.json &>/dev/null; then
+	EXIT=1
+	LINE=$(jq --stream 'if length == 1 then .[0][:-1] else .[0] end | if . == ["packageManager"] then input_line_number - 1 else empty end' package.json)
+	echo "::error file=package.json,line=$LINE::Version in package.json packageManager must be \"pnpm@$PNPM_VERSION\", to match .github/versions.sh."
+fi
 
 # - Check for incorrect next-version tokens.
 debug "Checking for incorrect next-version tokens."
diff --git a/.npmrc b/.npmrc
index 685f1ad31f63c..c1c907fa86634 100644
--- a/.npmrc
+++ b/.npmrc
@@ -25,3 +25,5 @@ resolution-mode = highest
 
 # @automattic/jetpack-webpack-config looks for this.
 jetpack-webpack-config-resolve-conditions=jetpack:src
+
+manage-package-manager-versions=false
diff --git a/package.json b/package.json
index b7d34e0aa51d2..347afccb62110 100644
--- a/package.json
+++ b/package.json
@@ -36,5 +36,6 @@
 	"engines": {
 		"node": "^22.9.0",
 		"pnpm": "^9.3.0 <9.12.0"
-	}
+	},
+	"packageManager": "pnpm@9.3.0"
 }