WooCommerce - Add checkbox field to the checkout

add-checkbox-to-checkout-woocommerce-functions.php

<?php

/**
 * Add checkbox field to the checkout
 **/

$myCheckboxKey = 'my_checkbox';

add_action('woocommerce_after_order_notes', 'my_custom_checkout_field');
function my_custom_checkout_field( $checkout ) {
 
    echo '<div id="my-new-field"><h3>'.__('My Checkbox: ').'</h3>';
 
    woocommerce_form_field( $myCheckboxKey, array(
        'type'          => 'checkbox',
        'class'         => array('input-checkbox'),
        'label'         => __('I have read and agreed.'),
        'required'  => true,
        ), $checkout->get_value( $myCheckboxKey ));
 
    echo '</div>';
}
 
/**
 * Process the checkout
 **/
add_action('woocommerce_checkout_process', 'my_custom_checkout_field_process');
 
function my_custom_checkout_field_process() {
    // Check if set, if its not set add an error.
    if (!$_POST[$myCheckboxKey])
        wc_add_notice( __('Please agree to my checkbox.'), 'error' );
}
 
/**
 * Update the order meta with field value
 **/
add_action('woocommerce_checkout_update_order_meta', 'my_custom_checkout_field_update_order_meta');
 
function my_custom_checkout_field_update_order_meta( $order_id ) {
    if ($_POST[$myCheckboxKey]) update_post_meta( $order_id, $myCheckboxKey, esc_attr($_POST[$myCheckboxKey]));
}

?>