diff --git c/modules/cart/commerce_cart.module w/modules/cart/commerce_cart.module
index 8274e3d..21e226e 100644
--- c/modules/cart/commerce_cart.module
+++ w/modules/cart/commerce_cart.module
@@ -1916,7 +1916,6 @@ function commerce_cart_add_to_cart_form($form, &$form_state, $line_item, $show_q
   // form with form IDs based on the $product_ids.
   $form['#validate'][] = 'commerce_cart_add_to_cart_form_validate';
   $form['#submit'][] = 'commerce_cart_add_to_cart_form_submit';
-
   return $form;
 }
 
@@ -2113,7 +2112,7 @@ function commerce_cart_field_formatter_info() {
     'commerce_cart_add_to_cart_form' => array(
       'label' => t('Add to Cart form'),
       'description' => t('Display an Add to Cart form for the referenced product.'),
-      'field types' => array('commerce_product_reference'),
+      'field types' => array('commerce_product_reference', 'entityreference'),
       'settings' => array(
         'show_quantity' => FALSE,
         'default_quantity' => 1,
@@ -2230,7 +2229,12 @@ function commerce_cart_field_formatter_view($entity_type, $entity, $field, $inst
   $product_ids = array();
 
   foreach ($items as $delta => $item) {
-    $product_ids[] = $item['product_id'];
+    if (isset($item['product_id'])) {
+      $product_ids[] = $item['product_id'];
+    }
+    elseif (module_exists('entityreference') && isset($item['target_id'])) {
+      $product_ids[] = $item['target_id'];
+    }
   }
 
   if ($display['type'] == 'commerce_cart_add_to_cart_form') {