diff --git a/cmd/flux/bootstrap_bitbucket_server.go b/cmd/flux/bootstrap_bitbucket_server.go
index 7cbfce73..105da32b 100644
--- a/cmd/flux/bootstrap_bitbucket_server.go
+++ b/cmd/flux/bootstrap_bitbucket_server.go
@@ -24,6 +24,7 @@ import (
 
 	"github.com/fluxcd/pkg/git"
 	"github.com/fluxcd/pkg/git/gogit"
+	"github.com/fluxcd/pkg/git/signature"
 	"github.com/spf13/cobra"
 
 	"github.com/fluxcd/flux2/v2/internal/flags"
@@ -288,6 +289,31 @@ func bootstrapBServerCmdRun(cmd *cobra.Command, args []string) error {
 		bootstrapOpts = append(bootstrapOpts, bootstrap.WithReconcile())
 	}
 
+	if bootstrapArgs.sshSigningKeyFile != "" {
+		pemBytes, err := os.ReadFile(bootstrapArgs.sshSigningKeyFile)
+		if err != nil {
+			return fmt.Errorf("failed to read SSH signing key file: %w", err)
+		}
+		pwd, err := effectiveSshSigningPassword()
+		if err != nil {
+			return err
+		}
+		bootstrapOpts = append(bootstrapOpts,
+			bootstrap.WithSSHCommitSigning(pemBytes, []byte(pwd)))
+	}
+
+	if bootstrapArgs.sshSigningReusePrivateKey {
+		pemBytes, err := os.ReadFile(bootstrapArgs.privateKeyFile)
+		if err != nil {
+			return fmt.Errorf("failed to read transport private key for signing: %w", err)
+		}
+		if _, err := signature.NewSSHSigner(pemBytes, []byte(gitArgs.password)); err != nil {
+			return fmt.Errorf("invalid signing key (reused from --private-key-file): %w", err)
+		}
+		bootstrapOpts = append(bootstrapOpts,
+			bootstrap.WithSSHCommitSigning(pemBytes, []byte(gitArgs.password)))
+	}
+
 	// Setup bootstrapper with constructed configs
 	b, err := bootstrap.NewGitProviderBootstrapper(gitClient, providerClient, kubeClient, bootstrapOpts...)
 	if err != nil {
diff --git a/cmd/flux/bootstrap_gitea.go b/cmd/flux/bootstrap_gitea.go
index 81a2d544..ad30e8bb 100644
--- a/cmd/flux/bootstrap_gitea.go
+++ b/cmd/flux/bootstrap_gitea.go
@@ -253,6 +253,12 @@ func bootstrapGiteaCmdRun(cmd *cobra.Command, args []string) error {
 		bootstrap.WithLogger(logger),
 		bootstrap.WithGitCommitSigning(entityList, bootstrapArgs.gpgPassphrase, bootstrapArgs.gpgKeyID),
 	}
+
+	if bootstrapArgs.sshSigningReusePrivateKey {
+		return fmt.Errorf("--ssh-signing-reuse-private-key is not supported by 'bootstrap gitea'; " +
+			"that subcommand generates the SSH transport key in-process and has no operator-supplied key to reuse")
+	}
+
 	if bootstrapArgs.sshHostname != "" {
 		bootstrapOpts = append(bootstrapOpts, bootstrap.WithSSHHostname(bootstrapArgs.sshHostname))
 	}
@@ -266,6 +272,19 @@ func bootstrapGiteaCmdRun(cmd *cobra.Command, args []string) error {
 		bootstrapOpts = append(bootstrapOpts, bootstrap.WithReconcile())
 	}
 
+	if bootstrapArgs.sshSigningKeyFile != "" {
+		pemBytes, err := os.ReadFile(bootstrapArgs.sshSigningKeyFile)
+		if err != nil {
+			return fmt.Errorf("failed to read SSH signing key file: %w", err)
+		}
+		pwd, err := effectiveSshSigningPassword()
+		if err != nil {
+			return err
+		}
+		bootstrapOpts = append(bootstrapOpts,
+			bootstrap.WithSSHCommitSigning(pemBytes, []byte(pwd)))
+	}
+
 	// Setup bootstrapper with constructed configs
 	b, err := bootstrap.NewGitProviderBootstrapper(gitClient, providerClient, kubeClient, bootstrapOpts...)
 	if err != nil {
diff --git a/cmd/flux/bootstrap_github.go b/cmd/flux/bootstrap_github.go
index a0c5974e..6ae1cb9a 100644
--- a/cmd/flux/bootstrap_github.go
+++ b/cmd/flux/bootstrap_github.go
@@ -260,6 +260,12 @@ func bootstrapGitHubCmdRun(cmd *cobra.Command, args []string) error {
 		bootstrap.WithLogger(logger),
 		bootstrap.WithGitCommitSigning(entityList, bootstrapArgs.gpgPassphrase, bootstrapArgs.gpgKeyID),
 	}
+
+	if bootstrapArgs.sshSigningReusePrivateKey {
+		return fmt.Errorf("--ssh-signing-reuse-private-key is not supported by 'bootstrap github'; " +
+			"that subcommand generates the SSH transport key in-process and has no operator-supplied key to reuse")
+	}
+
 	if bootstrapArgs.sshHostname != "" {
 		bootstrapOpts = append(bootstrapOpts, bootstrap.WithSSHHostname(bootstrapArgs.sshHostname))
 	}
@@ -273,6 +279,19 @@ func bootstrapGitHubCmdRun(cmd *cobra.Command, args []string) error {
 		bootstrapOpts = append(bootstrapOpts, bootstrap.WithReconcile())
 	}
 
+	if bootstrapArgs.sshSigningKeyFile != "" {
+		pemBytes, err := os.ReadFile(bootstrapArgs.sshSigningKeyFile)
+		if err != nil {
+			return fmt.Errorf("failed to read SSH signing key file: %w", err)
+		}
+		pwd, err := effectiveSshSigningPassword()
+		if err != nil {
+			return err
+		}
+		bootstrapOpts = append(bootstrapOpts,
+			bootstrap.WithSSHCommitSigning(pemBytes, []byte(pwd)))
+	}
+
 	// Setup bootstrapper with constructed configs
 	b, err := bootstrap.NewGitProviderBootstrapper(gitClient, providerClient, kubeClient, bootstrapOpts...)
 	if err != nil {
diff --git a/cmd/flux/bootstrap_gitlab.go b/cmd/flux/bootstrap_gitlab.go
index c1a16902..58e3e127 100644
--- a/cmd/flux/bootstrap_gitlab.go
+++ b/cmd/flux/bootstrap_gitlab.go
@@ -27,6 +27,7 @@ import (
 	"github.com/fluxcd/go-git-providers/gitprovider"
 	"github.com/fluxcd/pkg/git"
 	"github.com/fluxcd/pkg/git/gogit"
+	"github.com/fluxcd/pkg/git/signature"
 	"github.com/spf13/cobra"
 
 	"github.com/fluxcd/flux2/v2/internal/flags"
@@ -322,6 +323,31 @@ func bootstrapGitLabCmdRun(cmd *cobra.Command, args []string) error {
 		bootstrapOpts = append(bootstrapOpts, bootstrap.WithReconcile())
 	}
 
+	if bootstrapArgs.sshSigningKeyFile != "" {
+		pemBytes, err := os.ReadFile(bootstrapArgs.sshSigningKeyFile)
+		if err != nil {
+			return fmt.Errorf("failed to read SSH signing key file: %w", err)
+		}
+		pwd, err := effectiveSshSigningPassword()
+		if err != nil {
+			return err
+		}
+		bootstrapOpts = append(bootstrapOpts,
+			bootstrap.WithSSHCommitSigning(pemBytes, []byte(pwd)))
+	}
+
+	if bootstrapArgs.sshSigningReusePrivateKey {
+		pemBytes, err := os.ReadFile(bootstrapArgs.privateKeyFile)
+		if err != nil {
+			return fmt.Errorf("failed to read transport private key for signing: %w", err)
+		}
+		if _, err := signature.NewSSHSigner(pemBytes, []byte(gitArgs.password)); err != nil {
+			return fmt.Errorf("invalid signing key (reused from --private-key-file): %w", err)
+		}
+		bootstrapOpts = append(bootstrapOpts,
+			bootstrap.WithSSHCommitSigning(pemBytes, []byte(gitArgs.password)))
+	}
+
 	// Setup bootstrapper with constructed configs
 	b, err := bootstrap.NewGitProviderBootstrapper(gitClient, providerClient, kubeClient, bootstrapOpts...)
 	if err != nil {