diff --git a/blocksuite/affine/blocks/embed-doc/src/embed-synced-doc-block/embed-synced-doc-block.ts b/blocksuite/affine/blocks/embed-doc/src/embed-synced-doc-block/embed-synced-doc-block.ts
index 7560dc564..7b759429b 100644
--- a/blocksuite/affine/blocks/embed-doc/src/embed-synced-doc-block/embed-synced-doc-block.ts
+++ b/blocksuite/affine/blocks/embed-doc/src/embed-synced-doc-block/embed-synced-doc-block.ts
@@ -56,6 +56,9 @@ export class EmbedSyncedDocBlockComponent extends EmbedBlockComponent<EmbedSynce
   // Caches total bounds, includes all blocks and elements.
   private _cachedBounds: Bound | null = null;
 
+  private _hasRenderedSyncedView = false;
+  private _hasInitedFitEffect = false;
+
   private readonly _initEdgelessFitEffect = () => {
     const fitToContent = () => {
       if (this.isPageMode) return;
@@ -558,8 +561,6 @@ export class EmbedSyncedDocBlockComponent extends EmbedBlockComponent<EmbedSynce
         this._selectBlock();
       }
     });
-
-    this._initEdgelessFitEffect();
   }
 
   override renderBlock() {
@@ -587,12 +588,21 @@ export class EmbedSyncedDocBlockComponent extends EmbedBlockComponent<EmbedSynce
       );
     }
 
+    !this._hasRenderedSyncedView && (this._hasRenderedSyncedView = true);
+
     return this._renderSyncedView();
   }
 
   override updated(changedProperties: PropertyValues) {
     super.updated(changedProperties);
     this.syncedDocCard?.requestUpdate();
+
+    if (!this._hasInitedFitEffect && this._hasRenderedSyncedView) {
+      /* Register the resizeObserver AFTER syncdView viewport's own resizeObserver
+       * so that viewport.onResize() use up-to-date boundingClientRect values */
+      this._hasInitedFitEffect = true;
+      this._initEdgelessFitEffect();
+    }
   }
 
   @state()