Online PHP editor | output for nWNZj

<?php $arr1 = array( array('Class' => 'Class 1','Student' => array('Name one')), array('Class' => 'Class 2','Student' => array('Name one')), ); $arr2 = array( array('Class' => 'Class 1','Student' => array('Name two, Name three')), array('Class' => 'Class 2','Student' => array('Name Two, Name Three, Name Four')), ); $newList = []; array_map(function($value, $list) use (&$newList) { $newList[] = ['Class' => $value['Class'], 'Student' => array_merge($value['Student'], $list['Student'])]; }, $arr1, $arr2); print_r($newList);