diff --git a/includes/Api/CheckoutController.php b/includes/Api/CheckoutController.php
index 96e4df1..8459001 100644
--- a/includes/Api/CheckoutController.php
+++ b/includes/Api/CheckoutController.php
@@ -262,6 +262,60 @@ class CheckoutController {
                     update_user_meta($user_id, 'billing_email', sanitize_email($billing['email']));
                 }
             }
+        } else {
+            // Guest checkout - check if auto-register is enabled
+            $customer_settings = \WooNooW\Compat\CustomerSettingsProvider::get_settings();
+            $auto_register = $customer_settings['auto_register_members'] ?? false;
+            
+            if ($auto_register && !empty($payload['billing']['email'])) {
+                $email = sanitize_email($payload['billing']['email']);
+                
+                // Check if user already exists
+                $existing_user = get_user_by('email', $email);
+                
+                if ($existing_user) {
+                    // User exists - link order to them
+                    $order->set_customer_id($existing_user->ID);
+                } else {
+                    // Create new user account
+                    $password = wp_generate_password(12, true, true);
+                    
+                    $userdata = [
+                        'user_login'   => $email,
+                        'user_email'   => $email,
+                        'user_pass'    => $password,
+                        'first_name'   => sanitize_text_field($payload['billing']['first_name'] ?? ''),
+                        'last_name'    => sanitize_text_field($payload['billing']['last_name'] ?? ''),
+                        'display_name' => trim((sanitize_text_field($payload['billing']['first_name'] ?? '') . ' ' . sanitize_text_field($payload['billing']['last_name'] ?? ''))) ?: $email,
+                        'role'         => 'customer', // WooCommerce customer role
+                    ];
+                    
+                    $new_user_id = wp_insert_user($userdata);
+                    
+                    if (!is_wp_error($new_user_id)) {
+                        // Link order to new user
+                        $order->set_customer_id($new_user_id);
+                        
+                        // Set WooCommerce customer billing data
+                        $customer = new \WC_Customer($new_user_id);
+                        
+                        if (!empty($payload['billing']['first_name'])) $customer->set_billing_first_name(sanitize_text_field($payload['billing']['first_name']));
+                        if (!empty($payload['billing']['last_name'])) $customer->set_billing_last_name(sanitize_text_field($payload['billing']['last_name']));
+                        if (!empty($payload['billing']['email'])) $customer->set_billing_email(sanitize_email($payload['billing']['email']));
+                        if (!empty($payload['billing']['phone'])) $customer->set_billing_phone(sanitize_text_field($payload['billing']['phone']));
+                        if (!empty($payload['billing']['address_1'])) $customer->set_billing_address_1(sanitize_text_field($payload['billing']['address_1']));
+                        if (!empty($payload['billing']['city'])) $customer->set_billing_city(sanitize_text_field($payload['billing']['city']));
+                        if (!empty($payload['billing']['state'])) $customer->set_billing_state(sanitize_text_field($payload['billing']['state']));
+                        if (!empty($payload['billing']['postcode'])) $customer->set_billing_postcode(sanitize_text_field($payload['billing']['postcode']));
+                        if (!empty($payload['billing']['country'])) $customer->set_billing_country(sanitize_text_field($payload['billing']['country']));
+                        
+                        $customer->save();
+                        
+                        // Send new account email (WooCommerce will handle this automatically via hook)
+                        do_action('woocommerce_created_customer', $new_user_id, $userdata, $password);
+                    }
+                }
+            }
         }
 
         // Add items