diff --git a/cli/command/manifest/annotate.go b/cli/command/manifest/annotate.go
index a9507deb73f0..fd8102bfc088 100644
--- a/cli/command/manifest/annotate.go
+++ b/cli/command/manifest/annotate.go
@@ -10,6 +10,7 @@ import (
 	"slices"
 
 	"github.com/containerd/errdefs"
+	"github.com/containerd/platforms"
 	"github.com/docker/cli/cli"
 	"github.com/docker/cli/cli/command"
 	"github.com/docker/cli/cli/config"
@@ -139,8 +140,15 @@ func runManifestAnnotate(dockerCLI command.Cli, opts annotateOptions) error {
 		imageManifest.Descriptor.Platform.OSVersion = opts.osVersion
 	}
 
-	if !isValidOSArch(imageManifest.Descriptor.Platform.OS, imageManifest.Descriptor.Platform.Architecture) {
-		return fmt.Errorf("manifest entry for image has unsupported os/arch combination: %s/%s", opts.os, opts.arch)
+	// Validate platform syntax, without restricting OS/architecture combinations.
+	//
+	// TODO(thaJeztah): Implement a platforms.Validate in containerd/platforms and replace this code.
+	p := imageManifest.Descriptor.Platform
+	if p.OS == "" || p.Architecture == "" {
+		return fmt.Errorf("manifest entry for image has missing os/architecture: %q/%q", p.OS, p.Architecture)
+	}
+	if _, err := platforms.Parse(platforms.FormatAll(*p)); err != nil {
+		return fmt.Errorf("manifest entry for image has invalid platform: %w", err)
 	}
 	return manifestStore.Save(targetRef, imgRef, imageManifest)
 }
diff --git a/cli/command/manifest/annotate_test.go b/cli/command/manifest/annotate_test.go
index f2c924e45ffc..d50c54c83c78 100644
--- a/cli/command/manifest/annotate_test.go
+++ b/cli/command/manifest/annotate_test.go
@@ -58,15 +58,16 @@ func TestManifestAnnotate(t *testing.T) {
 	assert.ErrorContains(t, cmd.Execute(), expectedError)
 
 	cmd.SetArgs([]string{"example.com/list:v1", "example.com/alpine:3.0"})
-	cmd.Flags().Set("os", "freebsd")
-	cmd.Flags().Set("arch", "fake")
-	cmd.Flags().Set("os-version", "1")
-	cmd.Flags().Set("os-features", "feature1")
-	cmd.Flags().Set("variant", "v7")
-	expectedError = "manifest entry for image has unsupported os/arch combination"
+	assert.NilError(t, cmd.Flags().Set("os", "freebsd"))
+	assert.NilError(t, cmd.Flags().Set("arch", "<invalid>"))
+	assert.NilError(t, cmd.Flags().Set("os-version", "1"))
+	assert.NilError(t, cmd.Flags().Set("os-features", "feature1"))
+	assert.NilError(t, cmd.Flags().Set("variant", "v7"))
+
+	expectedError = "manifest entry for image has invalid platform"
 	assert.ErrorContains(t, cmd.Execute(), expectedError)
 
-	cmd.Flags().Set("arch", "arm")
+	assert.NilError(t, cmd.Flags().Set("arch", "arm"))
 	assert.NilError(t, cmd.Execute())
 
 	cmd = newInspectCommand(cli)
diff --git a/cli/command/manifest/util.go b/cli/command/manifest/util.go
index c10a98b0d8f4..49d359d8c028 100644
--- a/cli/command/manifest/util.go
+++ b/cli/command/manifest/util.go
@@ -9,53 +9,6 @@ import (
 	"github.com/docker/cli/cli/manifest/types"
 )
 
-type osArch struct {
-	os   string
-	arch string
-}
-
-// Remove any unsupported os/arch combo
-// list of valid os/arch values (see "Optional Environment Variables" section
-// of https://go.dev/doc/install/source
-// Added linux/s390x as we know System z support already exists
-// Keep in sync with _docker_manifest_annotate in contrib/completion/bash/docker
-var validOSArches = map[osArch]bool{
-	{os: "darwin", arch: "386"}:      true,
-	{os: "darwin", arch: "amd64"}:    true,
-	{os: "darwin", arch: "arm"}:      true,
-	{os: "darwin", arch: "arm64"}:    true,
-	{os: "dragonfly", arch: "amd64"}: true,
-	{os: "freebsd", arch: "386"}:     true,
-	{os: "freebsd", arch: "amd64"}:   true,
-	{os: "freebsd", arch: "arm"}:     true,
-	{os: "linux", arch: "386"}:       true,
-	{os: "linux", arch: "amd64"}:     true,
-	{os: "linux", arch: "arm"}:       true,
-	{os: "linux", arch: "arm64"}:     true,
-	{os: "linux", arch: "ppc64le"}:   true,
-	{os: "linux", arch: "mips64"}:    true,
-	{os: "linux", arch: "mips64le"}:  true,
-	{os: "linux", arch: "riscv64"}:   true,
-	{os: "linux", arch: "s390x"}:     true,
-	{os: "netbsd", arch: "386"}:      true,
-	{os: "netbsd", arch: "amd64"}:    true,
-	{os: "netbsd", arch: "arm"}:      true,
-	{os: "openbsd", arch: "386"}:     true,
-	{os: "openbsd", arch: "amd64"}:   true,
-	{os: "openbsd", arch: "arm"}:     true,
-	{os: "plan9", arch: "386"}:       true,
-	{os: "plan9", arch: "amd64"}:     true,
-	{os: "solaris", arch: "amd64"}:   true,
-	{os: "windows", arch: "386"}:     true,
-	{os: "windows", arch: "amd64"}:   true,
-}
-
-func isValidOSArch(os string, arch string) bool {
-	// check for existence of this combo
-	_, ok := validOSArches[osArch{os, arch}]
-	return ok
-}
-
 func normalizeReference(ref string) (reference.Named, error) {
 	namedRef, err := reference.ParseNormalizedNamed(ref)
 	if err != nil {
diff --git a/contrib/completion/bash/docker b/contrib/completion/bash/docker
index a78b08a6e473..b9b7a28ec263 100644
--- a/contrib/completion/bash/docker
+++ b/contrib/completion/bash/docker
@@ -4156,6 +4156,7 @@ _docker_manifest_annotate() {
 				amd64
 				arm
 				arm64
+				loong64
 				mips64
 				mips64le
 				ppc64le