diff --git a/src/cmd/cos_gpu_installer/internal/commands/install.go b/src/cmd/cos_gpu_installer/internal/commands/install.go
index 07d7541..5a4a50d 100644
--- a/src/cmd/cos_gpu_installer/internal/commands/install.go
+++ b/src/cmd/cos_gpu_installer/internal/commands/install.go
@@ -40,6 +40,7 @@
 	gcsDownloadBucket  string
 	gcsDownloadPrefix  string
 	nvidiaInstallerURL string
+	signatureURL       string
 	debug              bool
 	test               bool
 }
@@ -74,11 +75,15 @@
 		"The GCS path prefix when downloading COS artifacts."+
 			"If not set then the COS version build number (e.g. 13310.1041.38) will be used.")
 	f.StringVar(&c.nvidiaInstallerURL, "nvidia-installer-url", "",
-		"A URL to an nvidia-installer to use for driver installation. This flag is mutually exclusive with `-version`. This flag must be used with `-allow-unsigned-driver`. This flag is only for debugging.")
+		"A URL to an nvidia-installer to use for driver installation. This flag is mutually exclusive with `-version`. "+
+			"This flag must be used with `-allow-unsigned-driver`. This flag is only for debugging and testing.")
+	f.StringVar(&c.signatureURL, "signature-url", "",
+		"A URL to the driver signature. This flag can only be used together with `-test` and `-nvidia-installer-url` for for debugging and testing.")
 	f.BoolVar(&c.debug, "debug", false,
 		"Enable debug mode.")
 	f.BoolVar(&c.test, "test", false,
-		"Enable test mode.")
+		"Enable test mode. "+
+			"In test mode, `-nvidia-installer-url` can be used without `-allow-unsigned-driver`.")
 }
 
 func (c *InstallCommand) validateFlags() error {
@@ -88,6 +93,9 @@
 	if c.nvidiaInstallerURL != "" && c.unsignedDriver == false && c.test == false {
 		return stderrors.New("-nvidia-installer-url is set, and -allow-unsigned-driver is not; -nvidia-installer-url must be used with -allow-unsigned-driver if not in test mode")
 	}
+	if c.signatureURL != "" && (c.nvidiaInstallerURL == "" || c.test == false) {
+		return stderrors.New("-signature-url must be used with -nvidia-installer-url and -test")
+	}
 	return nil
 }
 
@@ -227,7 +235,11 @@
 	defer func() { callback <- 0 }()
 
 	if !c.unsignedDriver {
-		if err := signing.DownloadDriverSignatures(downloader, c.driverVersion); err != nil {
+		if c.signatureURL != "" {
+			if err := signing.DownloadDriverSignaturesFromURL(c.signatureURL); err != nil {
+				return errors.Wrap(err, "failed to download driver signature")
+			}
+		} else if err := signing.DownloadDriverSignatures(downloader, c.driverVersion); err != nil {
 			if strings.Contains(err.Error(), "404 Not Found") {
 				return fmt.Errorf("The GPU driver is not available for the COS version. Please wait for half a day and retry.")
 			}
diff --git a/src/cmd/cos_gpu_installer/internal/signing/signature.go b/src/cmd/cos_gpu_installer/internal/signing/signature.go
index 952b1bb..68126eb 100644
--- a/src/cmd/cos_gpu_installer/internal/signing/signature.go
+++ b/src/cmd/cos_gpu_installer/internal/signing/signature.go
@@ -7,6 +7,7 @@
 	"path/filepath"
 
 	"cos.googlesource.com/cos/tools.git/src/pkg/cos"
+	"cos.googlesource.com/cos/tools.git/src/pkg/utils"
 	log "github.com/golang/glog"
 	"github.com/pkg/errors"
 )
@@ -33,10 +34,38 @@
 		return errors.Wrapf(err, "failed to download driver signature for version %s", driverVersion)
 	}
 
-	tarballPath := filepath.Join(gpuDriverSigningDir, driverVersion+".signature.tar.gz")
+	if err := decompressSignature(driverVersion + ".signature.tar.gz"); err != nil {
+		return errors.Wrapf(err, "failed to decompress driver signature for version %s.", driverVersion)
+	}
+
+	return nil
+}
+
+// DownloadDriverSignaturesFromURL downloads GPU driver signatures from a provided URL.
+func DownloadDriverSignaturesFromURL(signatureURL string) error {
+	if err := os.MkdirAll(gpuDriverSigningDir, 0755); err != nil {
+		return errors.Wrapf(err, "failed to create signing dir %s", gpuDriverSigningDir)
+	}
+
+	log.Infof("Downloading driver signature from URL: %s", signatureURL)
+	signatureName := filepath.Base(signatureURL)
+	outputPath := filepath.Join(gpuDriverSigningDir, signatureName)
+	if err := utils.DownloadContentFromURL(signatureURL, outputPath, "driver signature"); err != nil {
+		return errors.Wrapf(err, "failed to download driver signature from URL %s.", signatureURL)
+	}
+
+	if err := decompressSignature(signatureName); err != nil {
+		return errors.Wrapf(err, "failed to decompress driver signature: %s.", signatureName)
+	}
+
+	return nil
+}
+
+func decompressSignature(signatureName string) error {
+	tarballPath := filepath.Join(gpuDriverSigningDir, signatureName)
 	log.Infof("Decompressing signature %s", tarballPath)
 	if err := extractSignatures(tarballPath, gpuDriverSigningDir); err != nil {
-		return errors.Wrapf(err, "failed to extract driver signatures for version %s", driverVersion)
+		return errors.Wrapf(err, "failed to extract driver signatures %s", signatureName)
 	}
 
 	// Create a dummy private key. We don't need private key to sign the driver
@@ -48,7 +77,6 @@
 	if err := f.Close(); err != nil {
 		return errors.Wrapf(err, "failed to close dummy key file in %s", filepath.Join(gpuDriverSigningDir, gpuDriverDummyKey))
 	}
-
 	return nil
 }