Add a custom SKU field to WooCommerce products.

woo-add-custom-sku.php

<?php

function jk_add_custom_sku() {
  $args = array(
    'label' => __( 'Custom SKU', 'woocommerce' ),
    'placeholder' => __( 'Enter custom SKU here', 'woocommerce' ),
    'id' => 'jk_sku',
    'desc_tip' => true,
    'description' => __( 'This SKU is for internal use only.', 'woocommerce' ),
  );
  woocommerce_wp_text_input( $args );
}
add_action( 'woocommerce_product_options_sku', 'jk_add_custom_sku' );

function jk_save_custom_meta( $post_id ) {
  // grab the SKU value
  $sku = isset( $_POST[ 'jk_sku' ] ) ? sanitize_text_field( $_POST[ 'jk_sku' ] ) : '';
  
  // grab the product
  $product = wc_get_product( $post_id );
  
  // save the custom SKU meta field
  $product->update_meta_data( 'jk_sku', $sku );
  $product->save();
}

add_action( 'woocommerce_process_product_meta', 'jk_save_custom_meta' );

Thanks for the code, i was looking for the same! Were do i need to paste this code or upload the file to?

Many thanks!
Itai

@ibd2004 add it to the theme's function file or create a separate plugin.

Thanks! Will it have the same behavior as the WP SKU field, including variable products?

Have just checked and it sadly not work for variable products, any idea how to make that happen?