diff --git a/core/modules/block_place/block_place.routing.yml b/core/modules/block_place/block_place.routing.yml
new file mode 100644
index 0000000..4d7c765
--- /dev/null
+++ b/core/modules/block_place/block_place.routing.yml
@@ -0,0 +1,8 @@
+block_place.admin_library:
+  path: 'admin/structure/block-place/library/{theme}'
+  defaults:
+    _controller: '\Drupal\block_place\Controller\PlaceBlockLibraryController::listBlocks'
+    _title: 'Place block'
+  requirements:
+    _access_theme: 'TRUE'
+    _permission: 'administer blocks'
diff --git a/core/modules/block_place/src/Controller/PlaceBlockLibraryController.php b/core/modules/block_place/src/Controller/PlaceBlockLibraryController.php
new file mode 100644
index 0000000..443336b
--- /dev/null
+++ b/core/modules/block_place/src/Controller/PlaceBlockLibraryController.php
@@ -0,0 +1,36 @@
+<?php
+
+namespace Drupal\block_place\Controller;
+
+use Drupal\block\Controller\BlockLibraryController;
+use Drupal\Component\Serialization\Json;
+use Symfony\Component\HttpFoundation\Request;
+
+/**
+ * Block library controller that extends block module's to use offcanvas tray.
+ *
+ * @package Drupal\block_place\Controller
+ */
+class PlaceBlockLibraryController extends BlockLibraryController {
+
+  /**
+   * {@inheritdoc}
+   */
+  public function listBlocks(Request $request, $theme) {
+    $build = parent::listBlocks($request, $theme);
+    // Alter all 'Place Block' links to use the Offcanvas tray.
+    if (isset($build['blocks']['#rows'])) {
+      foreach ($build['blocks']['#rows'] as &$row) {
+        if (isset($row['operations']['data']['#links']['add'])) {
+          $row['operations']['data']['#links']['add']['attributes']['data-dialog-type'] = 'dialog';
+          $row['operations']['data']['#links']['add']['attributes']['data-dialog-renderer'] = 'offcanvas';
+          $row['operations']['data']['#links']['add']['attributes']['data-dialog-options'] = Json::encode([
+            'width' => 425,
+          ]);
+        }
+      }
+    }
+    return $build;
+  }
+
+}
diff --git a/core/modules/block_place/src/Plugin/DisplayVariant/PlaceBlockPageVariant.php b/core/modules/block_place/src/Plugin/DisplayVariant/PlaceBlockPageVariant.php
index b2d3c33..d0e5f15 100644
--- a/core/modules/block_place/src/Plugin/DisplayVariant/PlaceBlockPageVariant.php
+++ b/core/modules/block_place/src/Plugin/DisplayVariant/PlaceBlockPageVariant.php
@@ -6,6 +6,7 @@
 use Drupal\block\Plugin\DisplayVariant\BlockPageVariant;
 use Drupal\Component\Serialization\Json;
 use Drupal\Core\Entity\EntityViewBuilderInterface;
+use Drupal\Core\Extension\ModuleHandlerInterface;
 use Drupal\Core\Routing\RedirectDestinationInterface;
 use Drupal\Core\Theme\ThemeManagerInterface;
 use Drupal\Core\Link;
@@ -36,6 +37,13 @@ class PlaceBlockPageVariant extends BlockPageVariant {
   protected $redirectDestination;
 
   /**
+   * The module handler.
+   *
+   * @var \Drupal\Core\Extension\ModuleHandlerInterface
+   */
+  protected $moduleHandler;
+
+  /**
    * Constructs a new PlaceBlockPageVariant.
    *
    * @param array $configuration
@@ -54,12 +62,15 @@ class PlaceBlockPageVariant extends BlockPageVariant {
    *   The theme manager.
    * @param \Drupal\Core\Routing\RedirectDestinationInterface $redirect_destination
    *   The redirect destination.
+   * @param \Drupal\Core\Extension\ModuleHandlerInterface $module_handler
+   *   The module handler.
    */
-  public function __construct(array $configuration, $plugin_id, $plugin_definition, BlockRepositoryInterface $block_repository, EntityViewBuilderInterface $block_view_builder, array $block_list_cache_tags, ThemeManagerInterface $theme_manager, RedirectDestinationInterface $redirect_destination) {
+  public function __construct(array $configuration, $plugin_id, $plugin_definition, BlockRepositoryInterface $block_repository, EntityViewBuilderInterface $block_view_builder, array $block_list_cache_tags, ThemeManagerInterface $theme_manager, RedirectDestinationInterface $redirect_destination, ModuleHandlerInterface $module_handler) {
     parent::__construct($configuration, $plugin_id, $plugin_definition, $block_repository, $block_view_builder, $block_list_cache_tags);
 
     $this->themeManager = $theme_manager;
     $this->redirectDestination = $redirect_destination;
+    $this->moduleHandler = $module_handler;
   }
 
   /**
@@ -74,7 +85,8 @@ public static function create(ContainerInterface $container, array $configuratio
       $container->get('entity_type.manager')->getViewBuilder('block'),
       $container->get('entity_type.manager')->getDefinition('block')->getListCacheTags(),
       $container->get('theme.manager'),
-      $container->get('redirect.destination')
+      $container->get('redirect.destination'),
+      $container->get('module_handler')
     );
   }
 
@@ -100,20 +112,34 @@ public function build() {
         $query['destination'] = $destination;
       }
       $title = $this->t('Place block<span class="visually-hidden"> in the %region region</span>', ['%region' => $region_name]);
+      // @todo Remove module exists check when offcanvas library moved into
+      //   core.services.yml. https://www.drupal.org/node/2784443
+      if ($this->moduleHandler->moduleExists('outside_in')) {
+        $place_block_route = 'block_place.admin_library';
+        $data_dialog_attributes = [
+          'data-dialog-type' => 'dialog',
+          'data-dialog-renderer' => 'offcanvas',
+        ];
+      }
+      else {
+        $place_block_route = 'block.admin_library';
+        $data_dialog_attributes = [
+          'data-dialog-type' => 'modal',
+          'data-dialog-options' => Json::encode([
+            'width' => 700,
+          ]),
+        ];
+      }
       $operations['block_description'] = [
         '#type' => 'inline_template',
         '#template' => '<div class="block-place-region">{{ link }}</div>',
         '#context' => [
-          'link' => Link::createFromRoute($title, 'block.admin_library', ['theme' => $theme_name], [
+          'link' => Link::createFromRoute($title, $place_block_route, ['theme' => $theme_name], [
             'query' => $query,
             'attributes' => [
               'title' => $title,
               'class' => ['use-ajax', 'button', 'button--small'],
-              'data-dialog-type' => 'modal',
-              'data-dialog-options' => Json::encode([
-                'width' => 700,
-              ]),
-            ],
+            ] + $data_dialog_attributes,
           ]),
         ],
       ];