diff --git a/components/reading_list/core/dual_reading_list_model.cc b/components/reading_list/core/dual_reading_list_model.cc
index d0c3df4728d0e..abe0344b72595 100644
--- a/components/reading_list/core/dual_reading_list_model.cc
+++ b/components/reading_list/core/dual_reading_list_model.cc
@@ -97,6 +97,7 @@ base::flat_set<GURL> DualReadingListModel::GetKeys() const {
 
 size_t DualReadingListModel::size() const {
   DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
+  DCHECK(loaded());
   DCHECK_EQ(unread_entry_count_ + read_entry_count_, GetKeys().size());
 
   return unread_entry_count_ + read_entry_count_;
@@ -496,6 +497,11 @@ void DualReadingListModel::RemoveObserver(ReadingListModelObserver* observer) {
 
 void DualReadingListModel::ReadingListModelBeganBatchUpdates(
     const ReadingListModel* model) {
+  DCHECK(!suppress_observer_notifications_);
+
+  if (!loaded()) {
+    return;
+  }
   ++current_batch_updates_count_;
   if (current_batch_updates_count_ == 1) {
     for (auto& observer : observers_) {
@@ -506,6 +512,11 @@ void DualReadingListModel::ReadingListModelBeganBatchUpdates(
 
 void DualReadingListModel::ReadingListModelCompletedBatchUpdates(
     const ReadingListModel* model) {
+  DCHECK(!suppress_observer_notifications_);
+
+  if (!loaded()) {
+    return;
+  }
   --current_batch_updates_count_;
   if (current_batch_updates_count_ == 0) {
     for (auto& observer : observers_) {
@@ -533,7 +544,7 @@ void DualReadingListModel::ReadingListModelLoaded(
 void DualReadingListModel::ReadingListWillRemoveEntry(
     const ReadingListModel* model,
     const GURL& url) {
-  if (suppress_observer_notifications_) {
+  if (!loaded() || suppress_observer_notifications_) {
     return;
   }
 
@@ -553,7 +564,7 @@ void DualReadingListModel::ReadingListWillRemoveEntry(
 void DualReadingListModel::ReadingListDidRemoveEntry(
     const ReadingListModel* model,
     const GURL& url) {
-  if (suppress_observer_notifications_) {
+  if (!loaded() || suppress_observer_notifications_) {
     return;
   }
 
@@ -572,7 +583,7 @@ void DualReadingListModel::ReadingListDidRemoveEntry(
 void DualReadingListModel::ReadingListWillMoveEntry(
     const ReadingListModel* model,
     const GURL& url) {
-  if (suppress_observer_notifications_) {
+  if (!loaded() || suppress_observer_notifications_) {
     return;
   }
 
@@ -586,7 +597,7 @@ void DualReadingListModel::ReadingListWillMoveEntry(
 void DualReadingListModel::ReadingListDidMoveEntry(
     const ReadingListModel* model,
     const GURL& url) {
-  if (suppress_observer_notifications_) {
+  if (!loaded() || suppress_observer_notifications_) {
     return;
   }
 
@@ -600,7 +611,7 @@ void DualReadingListModel::ReadingListDidMoveEntry(
 void DualReadingListModel::ReadingListWillAddEntry(
     const ReadingListModel* model,
     const ReadingListEntry& entry) {
-  if (suppress_observer_notifications_) {
+  if (!loaded() || suppress_observer_notifications_) {
     return;
   }
 
@@ -623,7 +634,7 @@ void DualReadingListModel::ReadingListDidAddEntry(
     const ReadingListModel* model,
     const GURL& url,
     reading_list::EntrySource source) {
-  if (suppress_observer_notifications_) {
+  if (!loaded() || suppress_observer_notifications_) {
     return;
   }
 
@@ -665,9 +676,10 @@ void DualReadingListModel::ReadingListDidUpdateEntry(
 }
 
 void DualReadingListModel::ReadingListDidApplyChanges(ReadingListModel* model) {
-  if (!suppress_observer_notifications_) {
-    NotifyObserversWithDidApplyChanges();
+  if (!loaded() || suppress_observer_notifications_) {
+    return;
   }
+  NotifyObserversWithDidApplyChanges();
 }
 
 DualReadingListModel::StorageStateForTesting
diff --git a/components/reading_list/core/dual_reading_list_model_unittest.cc b/components/reading_list/core/dual_reading_list_model_unittest.cc
index 95dd565b203b5..03eb3826d0fab 100644
--- a/components/reading_list/core/dual_reading_list_model_unittest.cc
+++ b/components/reading_list/core/dual_reading_list_model_unittest.cc
@@ -190,6 +190,24 @@ class DualReadingListModelTest : public testing::Test {
         /*initial_account_entries_builders=*/{});
   }
 
+  bool TriggerAccountStorageLoadCompletionSignedInSyncDisabled(
+      std::vector<TestEntryBuilder> initial_account_entries_builders = {}) {
+    auto metadata_batch = std::make_unique<syncer::MetadataBatch>();
+    sync_pb::ModelTypeState state;
+    state.set_initial_sync_state(
+        sync_pb::ModelTypeState_InitialSyncState_INITIAL_SYNC_DONE);
+    state.set_authenticated_account_id(kTestAccountId);
+    metadata_batch->SetModelTypeState(state);
+
+    std::vector<scoped_refptr<ReadingListEntry>> initial_account_entries;
+    for (auto entry_builder : initial_account_entries_builders) {
+      initial_account_entries.push_back(entry_builder.Build());
+    }
+
+    return account_model_storage_ptr_->TriggerLoadCompletion(
+        std::move(initial_account_entries), std::move(metadata_batch));
+  }
+
   bool TriggerStorageLoadCompletionSignedInSyncDisabled(
       std::vector<TestEntryBuilder> initial_local_entries_builders = {},
       std::vector<TestEntryBuilder> initial_account_entries_builders = {}) {
@@ -304,6 +322,25 @@ TEST_F(DualReadingListModelTest, MetaDataClearedBeforeModelLoaded) {
   EXPECT_EQ(0ul, dual_model_->size());
 }
 
+TEST_F(DualReadingListModelTest, UpdatesFromSyncBeforeTheLocalModelIsLoaded) {
+  ResetStorage();
+  TriggerAccountStorageLoadCompletionSignedInSyncDisabled(
+      /*initial_account_entries_builders=*/{
+          TestEntryBuilder(kUrl, clock_.Now())});
+
+  EXPECT_CALL(observer_, ReadingListWillRemoveEntry).Times(0);
+  EXPECT_CALL(observer_, ReadingListDidRemoveEntry).Times(0);
+  EXPECT_CALL(observer_, ReadingListWillAddEntry).Times(0);
+  EXPECT_CALL(observer_, ReadingListDidAddEntry).Times(0);
+  EXPECT_CALL(observer_, ReadingListDidApplyChanges).Times(0);
+
+  // DCHECKs verify that sync updates are issued as batch updates.
+  auto token = account_model_ptr_->BeginBatchUpdates();
+  account_model_ptr_->SyncRemoveEntry(kUrl);
+  account_model_ptr_->AddEntry(TestEntryBuilder(kUrl, clock_.Now()).Build(),
+                               reading_list::ADDED_VIA_SYNC);
+}
+
 TEST_F(DualReadingListModelTest, ReturnAccountModelSize) {
   ASSERT_TRUE(ResetStorageAndTriggerLoadCompletion(
       /*initial_local_or_syncable_entries_builders=*/{},