diff --git a/cmd/openapi/commands/overlay/apply.go b/cmd/openapi/commands/overlay/apply.go
index d8603a8..342c716 100644
--- a/cmd/openapi/commands/overlay/apply.go
+++ b/cmd/openapi/commands/overlay/apply.go
@@ -5,20 +5,21 @@ import (
 	"os"
 
 	"github.com/speakeasy-api/openapi/cmd/openapi/commands/cmdutil"
+	overlayPkg "github.com/speakeasy-api/openapi/overlay"
 	"github.com/speakeasy-api/openapi/overlay/loader"
 	"github.com/spf13/cobra"
 	"gopkg.in/yaml.v3"
 )
 
 var (
-	applyOverlayFlag string
-	applySchemaFlag  string
-	applyOutFlag     string
+	applyOverlayFlags []string
+	applySchemaFlag   string
+	applyOutFlag      string
 )
 
 var applyCmd = &cobra.Command{
-	Use:   "apply <overlay> [ <spec> ]",
-	Short: "Given an overlay, it will apply it to the spec. If omitted, spec will be loaded via extends (only from local file system).",
+	Use:   "apply [<overlay> [<spec>]]",
+	Short: "Given one or more overlays, it will apply them sequentially to the spec. If omitted, spec will be loaded via extends (only from local file system).",
 	Args:  cobra.RangeArgs(0, 2),
 	Run:   RunApply,
 	Example: `  # Apply overlay using positional arguments
@@ -35,29 +36,37 @@ var applyCmd = &cobra.Command{
 
   # Pipe spec via stdin and provide overlay as file
   cat spec.yaml | openapi overlay apply overlay.yaml -
-  cat spec.yaml | openapi overlay apply --overlay overlay.yaml --schema -`,
+  cat spec.yaml | openapi overlay apply --overlay overlay.yaml --schema -
+
+  # Apply multiple overlays sequentially (repeated flag)
+  openapi overlay apply --overlay base.yaml --overlay env.yaml --schema spec.yaml`,
 }
 
 func init() {
-	applyCmd.Flags().StringVar(&applyOverlayFlag, "overlay", "", "Path to the overlay file")
+	applyCmd.Flags().StringSliceVar(&applyOverlayFlags, "overlay", nil, "Path to an overlay file (can be repeated or comma-separated)")
 	applyCmd.Flags().StringVar(&applySchemaFlag, "schema", "", "Path to the OpenAPI specification file (use '-' for stdin)")
 	applyCmd.Flags().StringVarP(&applyOutFlag, "out", "o", "", "Output file path (defaults to stdout)")
 }
 
 func RunApply(cmd *cobra.Command, args []string) {
-	// Determine overlay file path from flag or positional argument
-	var overlayFile string
-	if applyOverlayFlag != "" {
-		overlayFile = applyOverlayFlag
+	// Build the list of overlay files from flags or positional args
+	var overlayFiles []string
+	if len(applyOverlayFlags) > 0 {
+		overlayFiles = applyOverlayFlags
 	} else if len(args) > 0 {
-		overlayFile = args[0]
+		overlayFiles = []string{args[0]}
 	} else {
-		Dief("overlay file is required (use --overlay flag or provide as first argument)")
+		Dief("at least one overlay file is required (use --overlay flag or provide as first argument)")
 	}
 
-	o, err := loader.LoadOverlay(overlayFile)
-	if err != nil {
-		Die(err)
+	// Load all overlays upfront (fail fast on parse errors)
+	overlays := make([]*overlayPkg.Overlay, 0, len(overlayFiles))
+	for _, f := range overlayFiles {
+		o, err := loader.LoadOverlay(f)
+		if err != nil {
+			Dief("Failed to load overlay %q: %s", f, err.Error())
+		}
+		overlays = append(overlays, o)
 	}
 
 	// Determine spec file path from flag or positional argument
@@ -68,8 +77,9 @@ func RunApply(cmd *cobra.Command, args []string) {
 		specFile = cmdutil.ArgAt(args, 1, "")
 	}
 
-	// Load spec from stdin or file
+	// Load spec from stdin or file (use first overlay's extends as fallback)
 	var ys *yaml.Node
+	var err error
 	specSource := specFile
 	if cmdutil.IsStdin(specFile) || (specFile == "" && cmdutil.StdinIsPiped()) {
 		fmt.Fprintf(os.Stderr, "Reading specification from stdin\n")
@@ -79,15 +89,17 @@ func RunApply(cmd *cobra.Command, args []string) {
 			Die(err)
 		}
 	} else {
-		ys, specSource, err = loader.LoadEitherSpecification(specFile, o)
+		ys, specSource, err = loader.LoadEitherSpecification(specFile, overlays[0])
 		if err != nil {
 			Die(err)
 		}
 	}
 
-	err = o.ApplyTo(ys)
-	if err != nil {
-		Dief("Failed to apply overlay to spec %q: %v", specSource, err)
+	// Apply all overlays sequentially
+	for i, o := range overlays {
+		if err := o.ApplyTo(ys); err != nil {
+			Dief("Failed to apply overlay %q (#%d) to spec %q: %v", overlayFiles[i], i+1, specSource, err)
+		}
 	}
 
 	// Write to output file if specified, otherwise stdout