diff --git a/features/site-create.feature b/features/site-create.feature
index f068115c3..9c53543dc 100644
--- a/features/site-create.feature
+++ b/features/site-create.feature
@@ -93,3 +93,160 @@ Feature: Create a new site on a WP multisite
       | blog_id | url                           |
       | 1       | http://localhost/         |
       | 2       | http://localhost/newsite/ |
+
+  Scenario: Create site with custom URL in subdomain multisite
+    Given a WP multisite subdomain install
+
+    When I run `wp site create --site-url=http://custom.example.com`
+    Then STDOUT should contain:
+      """
+      Success: Site 2 created: http://custom.example.com/
+      """
+
+    When I run `wp site list --fields=blog_id,url`
+    Then STDOUT should be a table containing rows:
+      | blog_id | url                        |
+      | 1       | https://example.com/       |
+      | 2       | http://custom.example.com/ |
+
+    When I run `wp --url=custom.example.com option get home`
+    Then STDOUT should be:
+      """
+      http://custom.example.com
+      """
+
+  Scenario: Create site with custom URL in subdirectory multisite
+    Given a WP multisite subdirectory install
+
+    When I run `wp site create --site-url=http://example.com/custom/path/`
+    Then STDOUT should contain:
+      """
+      Success: Site 2 created:
+      """
+    And STDOUT should contain:
+      """
+      ://example.com/custom/path/
+      """
+
+    When I run `wp site list --fields=blog_id,url`
+    Then STDOUT should contain:
+      """
+      ://example.com/custom/path/
+      """
+
+  Scenario: Create site with custom URL and explicit slug
+    Given a WP multisite subdomain install
+
+    When I run `wp site create --site-url=http://custom.example.com --slug=myslug`
+    Then STDOUT should contain:
+      """
+      Success: Site 2 created: http://custom.example.com/
+      """
+
+  Scenario: Error when neither slug nor site-url is provided
+    Given a WP multisite install
+
+    When I try `wp site create --title="Test Site"`
+    Then STDERR should be:
+      """
+      Error: Either --slug or --site-url must be provided.
+      """
+    And the return code should be 1
+
+  Scenario: Error when invalid URL format is provided
+    Given a WP multisite install
+
+    When I try `wp site create --site-url=not-a-valid-url`
+    Then STDERR should contain:
+      """
+      Error: Invalid URL format
+      """
+    And the return code should be 1
+
+  Scenario: Error when invalid scheme is provided
+    Given a WP multisite install
+
+    When I try `wp site create --site-url=ftp://example.com/site`
+    Then STDERR should be:
+      """
+      Error: Invalid URL scheme. Only http and https schemes are supported.
+      """
+    And the return code should be 1
+
+  Scenario: Error when root path provided without explicit slug
+    Given a WP multisite subdirectory install
+
+    When I try `wp site create --site-url=http://example.com/`
+    Then STDERR should be:
+      """
+      Error: Could not derive a valid slug from the URL path. Please provide --slug explicitly.
+      """
+    And the return code should be 1
+
+  Scenario: Create site with URL without trailing slash
+    Given a WP multisite subdirectory install
+
+    When I run `wp site create --site-url=http://example.com/notrailing`
+    Then STDOUT should contain:
+      """
+      Success: Site 2 created:
+      """
+    And STDOUT should contain:
+      """
+      ://example.com/notrailing/
+      """
+
+  Scenario: Error when numeric-only domain is provided without slug
+    Given a WP multisite subdomain install
+
+    When I try `wp site create --site-url=http://123.example.com`
+    Then STDERR should be:
+      """
+      Error: Could not derive a valid slug from the domain (numeric-only or empty slugs are not allowed). Please provide --slug explicitly.
+      """
+    And the return code should be 1
+
+  Scenario: Create site with different domain in subdirectory multisite shows warning
+    Given a WP multisite subdirectory install
+
+    When I try `wp site create --site-url=http://custom.example.com/mypath/`
+    Then STDERR should contain:
+      """
+      Warning: Using a different domain for a subdirectory multisite install may require additional configuration
+      """
+    And STDOUT should contain:
+      """
+      Success: Site 2 created:
+      """
+    And STDOUT should contain:
+      """
+      ://custom.example.com/mypath/
+      """
+
+  Scenario: Create site with both site-url and slug uses slug for internal operations
+    Given a WP multisite subdomain install
+
+    When I run `wp site create --site-url=http://custom.example.com --slug=myslug --porcelain`
+    Then STDOUT should be a number
+    And save STDOUT as {SITE_ID}
+
+    When I run `wp site list --site__in={SITE_ID} --field=url`
+    Then STDOUT should contain:
+      """
+      custom.example.com
+      """
+
+  Scenario: Preserve existing slug behavior
+    Given a WP multisite subdomain install
+
+    When I run `wp site create --slug=testsite`
+    Then STDOUT should contain:
+      """
+      Success: Site 2 created: http://testsite.example.com/
+      """
+
+    When I run `wp site list --fields=blog_id,url`
+    Then STDOUT should be a table containing rows:
+      | blog_id | url                          |
+      | 1       | https://example.com/         |
+      | 2       | http://testsite.example.com/ |
diff --git a/src/Site_Command.php b/src/Site_Command.php
index a0d6a9b38..11c0d6ebf 100644
--- a/src/Site_Command.php
+++ b/src/Site_Command.php
@@ -522,8 +522,15 @@ public function get( $args, $assoc_args ) {
 	 *
 	 * ## OPTIONS
 	 *
-	 * --slug=<slug>
+	 * [--slug=<slug>]
 	 * : Path for the new site. Subdomain on subdomain installs, directory on subdirectory installs.
+	 * Required if --site-url is not provided.
+	 *
+	 * [--site-url=<url>]
+	 * : Full URL for the new site. Use this to specify a custom domain instead of the auto-generated one.
+	 * For subdomain installs, this allows you to use a different base domain (e.g., 'http://site.example.com' instead of 'http://site.main.example.com').
+	 * For subdirectory installs, this allows you to use a different path.
+	 * If provided, --slug is optional and will be derived from the URL. If both --slug and --site-url are provided, --slug will be used as the base for internal operations (like user creation), while the domain/path from --site-url will be used for the actual site URL.
 	 *
 	 * [--title=<title>]
 	 * : Title of the new site. Default: prettified slug.
@@ -542,8 +549,17 @@ public function get( $args, $assoc_args ) {
 	 *
 	 * ## EXAMPLES
 	 *
+	 *     # Create a site with auto-generated domain
 	 *     $ wp site create --slug=example
 	 *     Success: Site 3 created: http://www.example.com/example/
+	 *
+	 *     # Create a site with a custom domain (subdomain multisite)
+	 *     $ wp site create --site-url=http://site.example.com
+	 *     Success: Site 4 created: http://site.example.com/
+	 *
+	 *     # Create a site with a custom subdirectory (subdirectory multisite)
+	 *     $ wp site create --site-url=http://example.com/custom/path/
+	 *     Success: Site 5 created: http://example.com/custom/path/
 	 */
 	public function create( $args, $assoc_args ) {
 		if ( ! is_multisite() ) {
@@ -552,7 +568,72 @@ public function create( $args, $assoc_args ) {
 
 		global $wpdb, $current_site;
 
-		$base = $assoc_args['slug'];
+		// Check if either slug or site-url is provided
+		$has_slug     = isset( $assoc_args['slug'] );
+		$has_site_url = isset( $assoc_args['site-url'] );
+
+		if ( ! $has_slug && ! $has_site_url ) {
+			WP_CLI::error( 'Either --slug or --site-url must be provided.' );
+		}
+
+		// If site URL is provided, parse it to get domain and path
+		$custom_domain = null;
+		$custom_path   = null;
+		$base          = null;
+
+		if ( $has_site_url ) {
+			$parsed_url = wp_parse_url( $assoc_args['site-url'] );
+			if ( ! isset( $parsed_url['host'] ) ) {
+				WP_CLI::error( 'Invalid URL format. Please provide a valid URL (e.g., http://site.example.com).' );
+			}
+
+			// Validate the scheme if present
+			if ( isset( $parsed_url['scheme'] ) && ! in_array( $parsed_url['scheme'], [ 'http', 'https' ], true ) ) {
+				WP_CLI::error( 'Invalid URL scheme. Only http and https schemes are supported.' );
+			}
+
+			// Sanitize domain and path
+			$custom_domain = sanitize_text_field( $parsed_url['host'] );
+			$custom_path   = isset( $parsed_url['path'] ) ? sanitize_text_field( '/' . ltrim( $parsed_url['path'], '/' ) ) : '/';
+
+			// Ensure path ends with /
+			if ( '/' !== substr( $custom_path, -1 ) ) {
+				$custom_path .= '/';
+			}
+
+			// Derive base/slug from the URL if not explicitly provided
+			if ( ! $has_slug ) {
+				if ( is_subdomain_install() ) {
+					// For subdomain installs, use the first part of the domain as the base
+					$domain_parts = explode( '.', $custom_domain );
+					$base         = $domain_parts[0];
+
+					// Validate that the derived base is suitable for use as a slug
+					if ( empty( $base ) || is_numeric( $base ) ) {
+						WP_CLI::error( 'Could not derive a valid slug from the domain (numeric-only or empty slugs are not allowed). Please provide --slug explicitly.' );
+					}
+
+					// Sanitize and lowercase the derived base
+					$base = strtolower( $base );
+				} else {
+					// For subdirectory installs, derive slug from the last part of the path.
+					$path_parts = array_filter( explode( '/', trim( $custom_path, '/' ) ) );
+					$base       = (string) array_pop( $path_parts );
+
+					// If base is empty (root path), require explicit slug.
+					if ( empty( $base ) ) {
+						WP_CLI::error( 'Could not derive a valid slug from the URL path. Please provide --slug explicitly.' );
+					}
+
+					// Sanitize and lowercase the derived base.
+					$base = strtolower( $base );
+				}
+			} else {
+				$base = $assoc_args['slug'];
+			}
+		} else {
+			$base = $assoc_args['slug'];
+		}
 
 		/**
 		 * @var string $title
@@ -603,10 +684,25 @@ public function create( $args, $assoc_args ) {
 			}
 		}
 
-		if ( is_subdomain_install() ) {
+		if ( null !== $custom_domain ) {
+			// A custom site URL was provided.
+			$newdomain = $custom_domain;
+			$path      = $custom_path;
+
+			// For subdirectory installs, warn if the domain is different from the network's domain.
+			if ( ! is_subdomain_install() ) {
+				$network_domain           = preg_replace( '|^www\.|', '', $current_site->domain );
+				$custom_domain_normalized = preg_replace( '|^www\.|', '', $custom_domain );
+				if ( $custom_domain_normalized !== $network_domain ) {
+					WP_CLI::warning( 'Using a different domain for a subdirectory multisite install may require additional configuration (such as domain mapping) to work properly.' );
+				}
+			}
+		} elseif ( is_subdomain_install() ) {
+			// No custom site URL, use the slug to generate the domain/path for subdomain install.
 			$newdomain = $base . '.' . preg_replace( '|^www\.|', '', $current_site->domain );
 			$path      = $current_site->path;
 		} else {
+			// No custom site URL, use the slug to generate the domain/path for subdirectory install.
 			$newdomain = $current_site->domain;
 			$path      = $current_site->path . $base . '/';
 		}