diff --git a/.github/workflows/scripts/windows/swift/install-swift-6.4.ps1 b/.github/workflows/scripts/windows/swift/install-swift-6.4.ps1
new file mode 100644
index 00000000..fe7a8aef
--- /dev/null
+++ b/.github/workflows/scripts/windows/swift/install-swift-6.4.ps1
@@ -0,0 +1,22 @@
+##===----------------------------------------------------------------------===##
+##
+## This source file is part of the Swift.org open source project
+##
+## Copyright (c) 2026 Apple Inc. and the Swift project authors
+## Licensed under Apache License v2.0 with Runtime Library Exception
+##
+## See https://swift.org/LICENSE.txt for license information
+## See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
+##
+##===----------------------------------------------------------------------===##
+. $PSScriptRoot\install-swift.ps1
+
+if ([System.Runtime.InteropServices.RuntimeInformation]::OSArchitecture -eq "Arm64") {
+    $SWIFT='https://download.swift.org/swift-6.4.0-release/windows10-arm64/swift-6.4.0-RELEASE/swift-6.4.0-RELEASE-windows10-arm64.exe'
+    $SWIFT_SHA256='f48e393634995cb589f547e40d64673bc641ca76b099697ba8227a8904be4a49'
+} else {
+    $SWIFT='https://download.swift.org/swift-6.4.0-release/windows10/swift-6.4.0-RELEASE/swift-6.4.0-RELEASE-windows10.exe'
+    $SWIFT_SHA256='76169a85bcba82854a0cd8f9655ffb74b3758d60c35a245457510095f2823c03'
+}
+
+Install-Swift -Url $SWIFT -Sha256 $SWIFT_SHA256
diff --git a/.github/workflows/swift_package_test.yml b/.github/workflows/swift_package_test.yml
index bd17987a..5c7bf628 100644
--- a/.github/workflows/swift_package_test.yml
+++ b/.github/workflows/swift_package_test.yml
@@ -45,7 +45,7 @@ on:
       linux_swift_versions:
         type: string
         description: "Include Linux Swift version list (JSON)"
-        default: "[ \"5.9\", \"5.10\", \"6.0\", \"6.1\", \"6.2\", \"6.3\", \"nightly-main\", \"nightly-6.4.x\"]"
+        default: "[ \"6.1\", \"6.2\", \"6.3\", \"6.4\", \"nightly-main\", \"nightly-6.4.x\"]"
       linux_exclude_swift_versions:
         type: string
         description: "Exclude Linux Swift version list (JSON)"
@@ -61,7 +61,7 @@ on:
       linux_static_sdk_versions:
         type: string
         description: "Static Linux Swift SDK version list (JSON)"
-        default: "[\"nightly-main\", \"nightly-6.4.x\", \"6.3\"]"
+        default: "[\"nightly-main\", \"nightly-6.4.x\", \"6.4\"]"
       linux_static_sdk_exclude_swift_versions:
         type: string
         description: "Exclude Static Linux Swift SDK version list (JSON)"
@@ -69,7 +69,7 @@ on:
       wasm_sdk_versions:
         type: string
         description: "Wasm Swift SDK version list (JSON)"
-        default: "[\"nightly-main\", \"nightly-6.4.x\", \"6.3\"]"
+        default: "[\"nightly-main\", \"nightly-6.4.x\", \"6.4\"]"
       wasm_exclude_swift_versions:
         type: string
         description: "Exclude Wasm Swift SDK version list (JSON)"
@@ -77,7 +77,7 @@ on:
       android_sdk_versions:
         type: string
         description: "Android Swift SDK version list (JSON)"
-        default: "[\"nightly-main\", \"nightly-6.4.x\", \"6.3\"]"
+        default: "[\"nightly-main\", \"nightly-6.4.x\", \"6.4\"]"
       android_exclude_swift_versions:
         type: string
         description: "Exclude Android Swift SDK version list (JSON)"
@@ -86,7 +86,7 @@ on:
         type: string
         description: "Include Windows Swift version list (JSON)"
         # "5.10" is omitted for Windows because the container image is broken.
-        default: "[\"5.9\", \"6.0\", \"6.1\", \"6.2\", \"6.3\", \"nightly-main\", \"nightly-6.4.x\"]"
+        default: "[\"6.1\", \"6.2\", \"6.3\", \"6.4\", \"nightly-main\", \"nightly-6.4.x\"]"
       windows_exclude_swift_versions:
         type: string
         description: "Exclude Windows Swift version list (JSON)"