diff --git a/options_element.js b/options_element.js
index f36dbe8..850b136 100644
--- a/options_element.js
+++ b/options_element.js
@@ -810,4 +810,20 @@ Drupal.theme.tableDragChangedWarning = function() {
   return '<span></span>';
 };
 
+/**
+ * Field module support for Options widgets.
+ */
+Drupal.behaviors.optionsElementFieldUI = {};
+Drupal.behaviors.optionsElementFieldUI.attach = function(context) {
+  var $cardinalityField = $(context).find('#edit-field-cardinality');
+  if ($cardinalityField.length) {
+    $cardinalityField.change(function() {
+      var optionsElementId = $(this).parents('fieldset:first').find('.form-type-options table').attr('id');
+      if (Drupal.optionElements[optionsElementId]) {
+        Drupal.optionElements[optionsElementId].setMultiple(this.value != 1);
+      }
+    }).trigger('change');
+  }
+}
+
 })(jQuery);
diff --git a/options_element.module b/options_element.module
index fd2e667..98efaae 100644
--- a/options_element.module
+++ b/options_element.module
@@ -174,3 +174,133 @@ function form_options_from_text($text, $key_type, $flat = FALSE, &$duplicates =
   module_load_include('inc', 'options_element');
   return _form_options_from_text($text, $key_type, $flat, $duplicates);
 }
+
+/**
+ * Implements hook_form_FORM_ID_alter().
+ */
+function options_element_form_field_ui_field_settings_form_alter(&$form, &$form_state) {
+  $type = $form['field']['type']['#value'];
+
+  if (in_array($type, _options_element_supported_field_types())) {
+    // Get default value.
+    $options = form_options_from_text($form['field']['settings']['allowed_values']['#default_value'], 'mixed');
+    // Toggled by default if options already set.
+    $key_type_toggled = !empty($options);
+
+    $element_overwrite = array(
+      '#options' => $options,
+      '#multiple' => FALSE,
+      '#key_type_toggled' => $key_type_toggled,
+      '#default_value_allowed' => FALSE,
+    );
+    _options_element_add_allowed_values_element($form, $element_overwrite);
+  }
+}
+
+/**
+ * Implements hook_form_FORM_ID_alter().
+ */
+function options_element_form_field_ui_field_edit_form_alter(&$form, &$form_state) {
+  $field = $form['#field'];
+
+  if (in_array($field['type'], _options_element_supported_field_types())) {
+
+    // Use options_element default widget instead of field widget.
+    $form['instance']['default_value_widget']['#access'] = FALSE;
+    // Language is hardcoded to 'und' in field_ui_default_value_widget().
+    $default_field_value = $form['instance']['default_value_widget'][$field['field_name']][LANGUAGE_NONE]['#default_value'];
+
+    // Overwrite 'allowed_values' element.
+    $element_overwrite = array(
+      '#options' => $field['settings']['allowed_values'],
+      '#multiple' => !($form['field']['cardinality']['#default_value'] == 1),
+      '#default_value' => $default_field_value,
+    );
+
+    _options_element_add_allowed_values_element($form, $element_overwrite);
+
+    // Add proper default value inside validate callback.
+    $form['#validate'][] = 'options_element_field_instance_settings_validate';
+  }
+}
+
+/**
+ * Element #after_build callback for the options list in Field UI.
+ */
+function options_element_field_settings_after_build($element, &$form_state) {
+  // Add original data for validating.
+  $element['options_field'] = array_merge($element['options_field'], $element['#original']);
+  // Standard validate.
+  $element['options_field']['#element_validate'][] = 'list_allowed_values_setting_validate';
+  return $element;
+}
+
+/**
+ * Form #validate callback for Field UI forms that use an options element.
+ */
+function options_element_field_settings_validate($form, &$form_state) {
+  if (!form_get_errors()) {
+    // Set allowed values.
+    form_set_value(
+      $form['field']['settings']['allowed_values'],
+      $form['field']['settings']['allowed_values']['#value']['options'],
+      $form_state
+    );
+  }
+}
+
+/**
+ * Form #validate callback for field_ui_field_edit_form().
+ */
+function options_element_field_instance_settings_validate($form, &$form_state) {
+  $field = $form['#field'];
+
+  if (!form_get_errors()) {
+    // Set default values.
+    $default_field_value_key = $form['instance']['default_value_widget'][$field['field_name']][LANGUAGE_NONE]['#value_key'];
+    // Create transposed array for field storage.
+    $default_values = options_array_transpose(array($default_field_value_key => (array)$form['field']['settings']['allowed_values']['#value']['default_value']));
+
+    form_set_value(
+      $form['instance']['default_value_widget'][$field['field_name']][LANGUAGE_NONE],
+      $default_values,
+      $form_state
+    );
+  }
+}
+
+/**
+ * Add options_element widget to form.
+ */
+function _options_element_add_allowed_values_element(&$form, $element) {
+  $default_element = array(
+    '#type' => 'options',
+    '#options' => array(),
+    '#key_type' => 'mixed', // Optimal for now.
+    '#key_type_toggle' => t('Custom keys'),
+    '#key_type_toggled' => TRUE,
+    '#after_build' => array('options_element_field_settings_after_build'),
+    '#access' => $form['field']['settings']['allowed_values']['#access'],
+    '#default_value' => '',
+    // Pass original data for validating.
+    '#original' => array(
+      '#title' => $form['field']['settings']['allowed_values']['#title'],
+      '#field_has_data' => $form['field']['settings']['allowed_values']['#field_has_data'],
+      '#field' => $form['field']['settings']['allowed_values']['#field'],
+      '#field_type' => $form['field']['settings']['allowed_values']['#field_type'],
+    )
+  );
+
+  $element = drupal_array_merge_deep($default_element, $element);
+  $form['field']['settings']['allowed_values'] = $element;
+
+  // Set proper allowed values in $form_state.
+  $form['#validate'][] = 'options_element_field_settings_validate';
+}
+
+/**
+ * Returns supported field types.
+ */
+function _options_element_supported_field_types() {
+  return array('list_integer', 'list_float', 'list_text');
+}