diff --git a/pkg/kn/commands/completion.go b/pkg/kn/commands/completion.go
index 365a5814e9..0d64452cba 100644
--- a/pkg/kn/commands/completion.go
+++ b/pkg/kn/commands/completion.go
@@ -20,26 +20,13 @@ import (
 	"github.com/spf13/cobra"
 )
 
-type CompletionFlags struct {
-	Zsh bool
-}
-
 func NewCompletionCommand(p *KnParams) *cobra.Command {
-	var completionFlags CompletionFlags
-
-	completionCmd := &cobra.Command{
+	return &cobra.Command{
 		Use:    "completion",
-		Short:  "Output shell completion code (default Bash)",
-		Hidden: true, // Don't show this in help listing.
+		Short:  "Output shell completion code (Bash)",
+		Hidden: true, // Don't show this in help listing
 		Run: func(cmd *cobra.Command, args []string) {
-			if completionFlags.Zsh {
-				cmd.Root().GenZshCompletion(os.Stdout)
-			} else {
-				cmd.Root().GenBashCompletion(os.Stdout)
-			}
+			cmd.Root().GenBashCompletion(os.Stdout)
 		},
 	}
-
-	completionCmd.Flags().BoolVar(&completionFlags.Zsh, "zsh", false, "Generates completion code for Zsh shell.")
-	return completionCmd
 }
diff --git a/pkg/kn/commands/completion_test.go b/pkg/kn/commands/completion_test.go
index f108c74220..7aa3585d55 100644
--- a/pkg/kn/commands/completion_test.go
+++ b/pkg/kn/commands/completion_test.go
@@ -38,7 +38,7 @@ func TestCompletion(t *testing.T) {
 	t.Run("creates a CompletionCommand", func(t *testing.T) {
 		setup()
 		assert.Equal(t, completionCmd.Use, "completion")
-		assert.Equal(t, completionCmd.Short, "Output shell completion code (default Bash)")
+		assert.Equal(t, completionCmd.Short, "Output shell completion code (Bash)")
 		assert.Assert(t, completionCmd.RunE == nil)
 	})
 
@@ -50,13 +50,4 @@ func TestCompletion(t *testing.T) {
 		completionCmd.Run(fakeRootCmd, []string{})
 		assert.Assert(t, ReadStdout(t) != "")
 	})
-
-	t.Run("returns completion code for ZSH", func(t *testing.T) {
-		setup()
-		CaptureStdout(t)
-		defer ReleaseStdout(t)
-
-		completionCmd.Run(fakeRootCmd, []string{"--zsh"})
-		assert.Assert(t, ReadStdout(t) != "")
-	})
 }