Using WordPress ‘the_category’ PHP filter

The the_category WordPress PHP filter modifies the category or list of categories for a given post.


add_filter('the_category', 'your_custom_function', 10, 3);

function your_custom_function($thelist, $separator, $parents) {
    // your custom code here
    return $thelist;


  • $thelist (string) – List of categories for the current post.
  • $separator (string) – Separator used between the categories.
  • $parents (string) – How to display the category parents. Accepts ‘multiple’, ‘single’, or empty.


More information

See WordPress Developer Resources: the_category


Change the separator between categories

Change the default separator to a comma and space.

function change_category_separator($thelist, $separator, $parents) {
    $separator = ', ';
    return implode($separator, array_filter(array_map('trim', explode($separator, $thelist))));
add_filter('the_category', 'change_category_separator', 10, 3);

Add an icon before each category

Add a custom icon before each category.

function add_icon_before_category($thelist, $separator, $parents) {
    return str_replace('<a', '<i class="your-icon-class"></i><a', $thelist);
add_filter('the_category', 'add_icon_before_category', 10, 3);

Remove specific category from the list

Remove a specific category from the category list by its ID.

function remove_specific_category($thelist, $separator, $parents) {
    $category_to_remove = 5; // Replace with your category ID
    return preg_replace('/<a href="[^>]*?category-' . $category_to_remove . '[^>]*>(.*?)<\/a>/', '', $thelist);
add_filter('the_category', 'remove_specific_category', 10, 3);

Open category links in a new tab.

function open_categories_in_new_tab($thelist, $separator, $parents) {
    return str_replace('<a', '<a target="_blank"', $thelist);
add_filter('the_category', 'open_categories_in_new_tab', 10, 3);

Display only the first category

Show only the first category in the category list.

function show_first_category_only($thelist, $separator, $parents) {
    $categories = array_filter(array_map('trim', explode($separator, $thelist)));
    return reset($categories);
add_filter('the_category', 'show_first_category_only', 10, 3);