Append new array in existing array field $orderList = $this->__pageModel->getOrderByCustomerId($formData['customer_id']); $newArray = []; foreach ($orderList as $order => $value) { $newArray[$order] = $value; $newArray[$order]['line_items'] = $this->__orderLineItemModel->getByOrderId($value['id']); } return $this->respond(array( 'status' => 'success', 'message' => 'Order list listed successfully', 'data' => $newArray )); New array added $newArray[$order]['line_items'] = $this->__orderLineItemModel->getByOrderId($value['id']);