Generally, there may not be much instances where you need to get category slug using ID, but knowing the method will help you while handling certain WordPress themes. By using a simple php function you can get the category slug through ID.

Paste the below code in your theme’s functions.php file and save changes.

function get_cat_slug($cat_id) {
	$cat_id = (int) $cat_id;
	$category = &get_category($cat_id);
	return $category->slug;
}

You can call the above function by using the below line of code.

<?php echo get_cat_slug(5); ?>

Since 5 is entered, the code will return the category slug corresponding to ID 5.