get_categories 将完成这项工作。

get_categories(\'taxonomy=taxonomy_name&type=custom_post_type\'); 

你试过什么吗？像这样的？

<?php 

$args=array(
  \'object_type\' => array(\'event\') 
); 

$output = \'names\'; // or objects
$operator = \'and\'; // \'and\' or \'or\'
$taxonomies=get_taxonomies($args,$output,$operator); 
if  ($taxonomies) {
  foreach ($taxonomies  as $taxonomy ) {
    echo \'<p>\'. $taxonomy. \'</p>\';
  }
}
?>

$taxonomies = get_taxonomies( [ \'object_type\' => [ \'custom_post_type\' ] ] );

使用get_object_taxonomies (https://developer.wordpress.org/reference/functions/get_object_taxonomies/), 以自定义帖子类型或帖子对象的名称作为参数：

$taxonomies = get_object_taxonomies(\'custom_post_type\');
$taxonomies = get_object_taxonomies($custom_post_object);

很抱歉提出了一个旧帖子，但我在为我的用例寻找答案时遇到了这个问题。

我想检索一个post类型的所有可用分类法，还想检索每个分类法的所有可用术语。

感谢Nick B为我提供了正确的答案：https://wordpress.stackexchange.com/a/357448/198353

// get a list of available taxonomies for a post type
$taxonomies = get_taxonomies([\'object_type\' => [\'your_post_type\']]);

$taxonomyTerms = [];

// loop over your taxonomies
foreach ($taxonomies as $taxonomy)
{
  // retrieve all available terms, including those not yet used
  $terms    = get_terms([\'taxonomy\' => $taxonomy, \'hide_empty\' => false]);

  // make sure $terms is an array, as it can be an int (count) or a WP_Error
  $hasTerms = is_array($terms) && $terms;

  if($hasTerms)
  {
    $taxonomyTerms[$taxonomy] = $terms;        
  }
}

get_post_taxonomies()

https://developer.wordpress.org/reference/functions/get_post_taxonomies/