diff --git a/plugin/evm/atomic/sync/syncer.go b/plugin/evm/atomic/sync/syncer.go
index 9d963f2899..f161ecfb70 100644
--- a/plugin/evm/atomic/sync/syncer.go
+++ b/plugin/evm/atomic/sync/syncer.go
@@ -146,6 +146,23 @@ func (s *Syncer) Sync(ctx context.Context) error {
 	return s.syncer.Sync(ctx)
 }
 
+// UpdateSyncTarget updates the target summary to sync to.
+// TODO(alarso16): see https://github.com/ava-labs/coreth/issues/1143
+func (*Syncer) UpdateSyncTarget(message.Syncable) error {
+	return errors.New("not yet implemented")
+}
+
+// Finalize is called after Sync completes to ensure all data matches the expected state.
+// This may block after UpdateSyncTarget is implemented.
+func (s *Syncer) Finalize(_ context.Context, summary message.Syncable) error {
+	// Ensure we synced to the expected target height.
+	if summary.Height() != s.targetHeight {
+		return fmt.Errorf("expected to sync to height %d but synced to %d", s.targetHeight, summary.Height())
+	}
+
+	return nil
+}
+
 // addZeroes returns the big-endian representation of `height`, prefixed with [common.HashLength] zeroes.
 func addZeroes(height uint64) []byte {
 	// Key format is [height(8 bytes)][blockchainID(32 bytes)]. Start should be the
diff --git a/plugin/evm/vmsync/doubles_test.go b/plugin/evm/vmsync/doubles_test.go
index e0c6d3e030..743ab4f9da 100644
--- a/plugin/evm/vmsync/doubles_test.go
+++ b/plugin/evm/vmsync/doubles_test.go
@@ -9,9 +9,13 @@ import (
 	"sync"
 	"time"
 
+	"github.com/ava-labs/coreth/plugin/evm/message"
+
 	syncpkg "github.com/ava-labs/coreth/sync"
 )
 
+var _ syncpkg.Syncer = FuncSyncer{}
+
 // FuncSyncer adapts a function to the simple Syncer shape used in tests. It is
 // useful for defining small, behavior-driven syncers inline.
 type FuncSyncer struct {
@@ -21,12 +25,14 @@ type FuncSyncer struct {
 // Sync calls the wrapped function and returns its result.
 func (f FuncSyncer) Sync(ctx context.Context) error { return f.fn(ctx) }
 
+// Unnecessary for these tests.
+func (FuncSyncer) UpdateSyncTarget(message.Syncable) error          { return nil }
+func (FuncSyncer) Finalize(context.Context, message.Syncable) error { return nil }
+
 // Name returns the provided name or a default if unspecified.
 func (FuncSyncer) Name() string { return "Test Name" }
 func (FuncSyncer) ID() string   { return "test_id" }
 
-var _ syncpkg.Syncer = FuncSyncer{}
-
 // NewBarrierSyncer returns a syncer that, upon entering Sync, calls wg.Done() to
 // signal it has started, then blocks until either:
 //   - `releaseCh` is closed, returning nil; or
diff --git a/plugin/evm/vmsync/registry.go b/plugin/evm/vmsync/registry.go
index f6895807e3..1be980db17 100644
--- a/plugin/evm/vmsync/registry.go
+++ b/plugin/evm/vmsync/registry.go
@@ -7,6 +7,7 @@ import (
 	"context"
 	"errors"
 	"fmt"
+	"sync"
 
 	"github.com/ava-labs/libevm/log"
 	"golang.org/x/sync/errgroup"
@@ -16,7 +17,10 @@ import (
 	synccommon "github.com/ava-labs/coreth/sync"
 )
 
-var errSyncerAlreadyRegistered = errors.New("syncer already registered")
+var (
+	errSyncerAlreadyRegistered    = errors.New("syncer already registered")
+	errUpdateSyncTargetNotAllowed = errors.New("UpdateSyncTarget not allowed while syncers are not running")
+)
 
 // SyncerTask represents a single syncer with its name for identification.
 type SyncerTask struct {
@@ -28,6 +32,11 @@ type SyncerTask struct {
 type SyncerRegistry struct {
 	syncers         []SyncerTask
 	registeredNames map[string]bool // Track registered IDs to prevent duplicates.
+
+	// This lock protects access to target and updateTargetAllowed.
+	targetLock          sync.Mutex
+	target              message.Syncable
+	updateTargetAllowed bool // Only allowed while syncers are running.
 }
 
 // NewSyncerRegistry creates a new empty syncer registry.
@@ -61,12 +70,12 @@ func (r *SyncerRegistry) RunSyncerTasks(ctx context.Context, summary message.Syn
 	summaryBlockHashHex := summary.GetBlockHash().Hex()
 	blockHeight := summary.Height()
 
-	g, ctx := errgroup.WithContext(ctx)
+	g, egCtx := errgroup.WithContext(ctx)
 
 	for _, task := range r.syncers {
 		g.Go(func() error {
 			log.Info("starting syncer", "name", task.name, "summary", summaryBlockHashHex, "height", blockHeight)
-			if err := task.syncer.Sync(ctx); err != nil {
+			if err := task.syncer.Sync(egCtx); err != nil {
 				log.Error("failed syncing", "name", task.name, "summary", summaryBlockHashHex, "height", blockHeight, "err", err)
 				return fmt.Errorf("%s failed: %w", task.name, err)
 			}
@@ -76,11 +85,61 @@ func (r *SyncerRegistry) RunSyncerTasks(ctx context.Context, summary message.Syn
 		})
 	}
 
+	// Allow UpdateSyncTarget calls while waiting for syncers to complete.
+	r.targetLock.Lock()
+	r.updateTargetAllowed = true
+	r.target = summary
+	r.targetLock.Unlock()
+
 	if err := g.Wait(); err != nil {
 		return err
 	}
 
 	log.Info("all syncers completed successfully", "count", len(r.syncers), "summary", summaryBlockHashHex)
 
+	// At this point, UpdateSyncTarget should no longer be called, so we should prevent it.
+	r.targetLock.Lock()
+	r.updateTargetAllowed = false
+	finalTarget := r.target
+	r.targetLock.Unlock()
+
+	// Finalize each syncer to ensure all data matches the expected state.
+	// Use a new error group to finalize in parallel.
+	g, egCtx = errgroup.WithContext(ctx)
+	for _, task := range r.syncers {
+		log.Info("finalizing syncer", "name", task.name, "summary", summaryBlockHashHex, "height", blockHeight)
+		g.Go(func() error {
+			if err := task.syncer.Finalize(egCtx, finalTarget); err != nil {
+				log.Error("failed finalizing", "name", task.name, "summary", summaryBlockHashHex, "height", blockHeight, "err", err)
+				return fmt.Errorf("%s finalize failed: %w", task.name, err)
+			}
+			return nil
+		})
+	}
+
+	return g.Wait()
+}
+
+// UpdateSyncTarget updates the target for all registered syncers.
+func (r *SyncerRegistry) UpdateSyncTarget(summary message.Syncable) error {
+	r.targetLock.Lock()
+	defer r.targetLock.Unlock()
+
+	if !r.updateTargetAllowed {
+		return errUpdateSyncTargetNotAllowed
+	}
+
+	// Since UpdateSyncTarget can block, we call each syncer in its own goroutine.
+	var eg errgroup.Group
+	for _, task := range r.syncers {
+		eg.Go(func() error {
+			return task.syncer.UpdateSyncTarget(summary)
+		})
+	}
+	if err := eg.Wait(); err != nil {
+		return fmt.Errorf("failed to update sync target: %w", err)
+	}
+
+	r.target = summary
 	return nil
 }
diff --git a/plugin/evm/vmsync/registry_test.go b/plugin/evm/vmsync/registry_test.go
index 2a85661444..226f0f0be4 100644
--- a/plugin/evm/vmsync/registry_test.go
+++ b/plugin/evm/vmsync/registry_test.go
@@ -24,9 +24,11 @@ var _ syncpkg.Syncer = (*mockSyncer)(nil)
 
 // mockSyncer implements [syncpkg.Syncer] for testing.
 type mockSyncer struct {
-	name      string
-	syncError error
-	started   bool // Track if already started
+	name           string
+	syncError      error
+	started        bool // Track if already started
+	updateCount    int  // Track number of UpdateSyncTarget calls
+	finalizeTarget message.Syncable
 }
 
 func newMockSyncer(name string, syncError error) *mockSyncer {
@@ -38,6 +40,16 @@ func (m *mockSyncer) Sync(context.Context) error {
 	return m.syncError
 }
 
+func (m *mockSyncer) UpdateSyncTarget(message.Syncable) error {
+	m.updateCount++
+	return nil
+}
+
+func (m *mockSyncer) Finalize(_ context.Context, target message.Syncable) error {
+	m.finalizeTarget = target
+	return nil
+}
+
 func (m *mockSyncer) Name() string { return m.name }
 func (m *mockSyncer) ID() string   { return m.name }
 
@@ -47,9 +59,17 @@ type namedSyncer struct {
 	syncer syncpkg.Syncer
 }
 
-func (n *namedSyncer) Sync(ctx context.Context) error { return n.syncer.Sync(ctx) }
 func (n *namedSyncer) Name() string                   { return n.name }
 func (n *namedSyncer) ID() string                     { return n.name }
+func (n *namedSyncer) Sync(ctx context.Context) error { return n.syncer.Sync(ctx) }
+
+func (n *namedSyncer) UpdateSyncTarget(target message.Syncable) error {
+	return n.syncer.UpdateSyncTarget(target)
+}
+
+func (n *namedSyncer) Finalize(ctx context.Context, summary message.Syncable) error {
+	return n.syncer.Finalize(ctx, summary)
+}
 
 // syncerConfig describes a test syncer setup for RunSyncerTasks table tests.
 type syncerConfig struct {
@@ -307,6 +327,73 @@ func TestSyncerRegistry_NoSyncersRegistered(t *testing.T) {
 	require.NoError(t, registry.RunSyncerTasks(ctx, newTestClientSummary(t)))
 }
 
+func TestSyncerRegistry_UpdateSyncTarget(t *testing.T) {
+	t.Parallel()
+
+	registry := NewSyncerRegistry()
+	ctx, cancel := utilstest.NewTestContext(t)
+	t.Cleanup(cancel)
+
+	var allStartedWG sync.WaitGroup
+	allStartedWG.Add(1)
+	releaseCh := make(chan struct{})
+	barrierSyncer := NewBarrierSyncer(&allStartedWG, releaseCh)
+	registry.Register(barrierSyncer)
+
+	// Create a tracked syncer to verify UpdateSyncTarget calls
+	syncer := newMockSyncer("UpdateTargetSyncer", nil)
+	registry.Register(syncer)
+
+	doneCh := make(chan error, 1)
+	go func() { doneCh <- registry.RunSyncerTasks(ctx, newTestClientSummary(t)) }()
+
+	utilstest.WaitGroupWithTimeout(t, &allStartedWG, 2*time.Second, "timed out waiting for barrier syncers to start")
+
+	customSummary, err := message.NewBlockSyncSummary(common.HexToHash("0xabcdef"), 1234, common.HexToHash("0xabcdef"))
+	require.NoError(t, err)
+	require.NoError(t, registry.UpdateSyncTarget(customSummary))
+	close(releaseCh)
+
+	require.NoError(t, utilstest.WaitErrWithTimeout(t, doneCh, 4*time.Second))
+	require.Equal(t, 1, syncer.updateCount)
+	require.Equal(t, customSummary, syncer.finalizeTarget)
+}
+
+func TestSyncerRegistry_UpdateSyncTargetNotAllowed(t *testing.T) {
+	t.Parallel()
+
+	registry := NewSyncerRegistry()
+	ctx, cancel := utilstest.NewTestContext(t)
+	t.Cleanup(cancel)
+
+	const numUpdateSyncers = 3
+	var mockSyncers []*mockSyncer
+	for i := 0; i < numUpdateSyncers; i++ {
+		name := fmt.Sprintf("UpdateSyncer-%d", i)
+		mockSyncer := newMockSyncer(name, nil)
+		mockSyncers = append(mockSyncers, mockSyncer)
+		require.NoError(t, registry.Register(&namedSyncer{name: name, syncer: mockSyncer}))
+	}
+
+	summary := newTestClientSummary(t)
+
+	// Call UpdateSyncTarget before starting syncers
+	err := registry.UpdateSyncTarget(summary)
+	require.ErrorIs(t, err, errUpdateSyncTargetNotAllowed)
+
+	// First call to RunSyncerTasks
+	require.NoError(t, registry.RunSyncerTasks(ctx, summary))
+
+	// Call UpdateSyncTarget after syncers have completed
+	err = registry.UpdateSyncTarget(summary)
+	require.ErrorIs(t, err, errUpdateSyncTargetNotAllowed)
+
+	// Verify UpdateSyncTarget was not called for each syncer
+	for i, mockSyncer := range mockSyncers {
+		require.Zero(t, mockSyncer.updateCount, "UpdateSyncTarget was called for syncer %d", i)
+	}
+}
+
 func newTestClientSummary(t *testing.T) message.Syncable {
 	t.Helper()
 	summary, err := message.NewBlockSyncSummary(common.HexToHash("0xdeadbeef"), 1000, common.HexToHash("0xdeadbeef"))
diff --git a/sync/blocksync/syncer.go b/sync/blocksync/syncer.go
index ca69a6dabc..489c4df18b 100644
--- a/sync/blocksync/syncer.go
+++ b/sync/blocksync/syncer.go
@@ -13,6 +13,8 @@ import (
 	"github.com/ava-labs/libevm/ethdb"
 	"github.com/ava-labs/libevm/log"
 
+	"github.com/ava-labs/coreth/plugin/evm/message"
+
 	syncpkg "github.com/ava-labs/coreth/sync"
 	statesyncclient "github.com/ava-labs/coreth/sync/client"
 )
@@ -20,9 +22,10 @@ import (
 const blocksPerRequest = 32
 
 var (
-	_                        syncpkg.Syncer = (*BlockSyncer)(nil)
-	errBlocksToFetchRequired                = errors.New("blocksToFetch must be > 0")
-	errFromHashRequired                     = errors.New("fromHash must be non-zero when fromHeight > 0")
+	_ syncpkg.Syncer = (*BlockSyncer)(nil)
+
+	errBlocksToFetchRequired = errors.New("blocksToFetch must be > 0")
+	errFromHashRequired      = errors.New("fromHash must be non-zero when fromHeight > 0")
 )
 
 type BlockSyncer struct {
@@ -112,3 +115,15 @@ func (s *BlockSyncer) Sync(ctx context.Context) error {
 	log.Info("fetched blocks from peer", "total", blocksToFetch)
 	return batch.Write()
 }
+
+// UpdateSyncTarget updates the target summary to sync to.
+// TODO(alarso16): see https://github.com/ava-labs/coreth/issues/1260
+func (*BlockSyncer) UpdateSyncTarget(message.Syncable) error {
+	return errors.New("not yet implemented")
+}
+
+// Finalize asserts that all blocks have been requested and written to disk.
+// This is a no-op until UpdateSyncTarget is implemented.
+func (*BlockSyncer) Finalize(context.Context, message.Syncable) error {
+	return nil
+}
diff --git a/sync/statesync/code_syncer.go b/sync/statesync/code_syncer.go
index 3fdda1f6c9..4eb1db4f20 100644
--- a/sync/statesync/code_syncer.go
+++ b/sync/statesync/code_syncer.go
@@ -5,6 +5,7 @@ package statesync
 
 import (
 	"context"
+	"errors"
 	"fmt"
 	"sync"
 
@@ -115,6 +116,17 @@ func (c *CodeSyncer) Sync(ctx context.Context) error {
 	return eg.Wait()
 }
 
+// UpdateSyncTarget is not yet implemented.
+// TODO(alarso16): see https://github.com/ava-labs/coreth/issues/1341
+func (*CodeSyncer) UpdateSyncTarget(message.Syncable) error {
+	return errors.New("not yet implemented")
+}
+
+// Finalize is currently a no-op since UpdateSyncTarget is not implemented.
+func (*CodeSyncer) Finalize(context.Context, message.Syncable) error {
+	return nil
+}
+
 // work fulfills any incoming requests from the producer channel by fetching code bytes from the network
 // and fulfilling them by updating the database.
 func (c *CodeSyncer) work(ctx context.Context) error {
diff --git a/sync/statesync/state_syncer.go b/sync/statesync/state_syncer.go
index adcf1809d8..fffb967635 100644
--- a/sync/statesync/state_syncer.go
+++ b/sync/statesync/state_syncer.go
@@ -17,6 +17,7 @@ import (
 	"golang.org/x/sync/errgroup"
 
 	"github.com/ava-labs/coreth/core/state/snapshot"
+	"github.com/ava-labs/coreth/plugin/evm/message"
 
 	syncpkg "github.com/ava-labs/coreth/sync"
 	syncclient "github.com/ava-labs/coreth/sync/client"
@@ -30,9 +31,11 @@ const (
 )
 
 var (
-	_                           syncpkg.Syncer = (*stateSync)(nil)
-	errCodeRequestQueueRequired                = errors.New("code request queue is required")
-	errLeafsRequestSizeRequired                = errors.New("leafs request size must be > 0")
+	_ syncpkg.Syncer = (*stateSync)(nil)
+
+	errCodeRequestQueueRequired  = errors.New("code request queue is required")
+	errDynamicSyncerNotSupported = errors.New("dynamic syncer not supported")
+	errLeafsRequestSizeRequired  = errors.New("leafs request size must be > 0")
 )
 
 // stateSync keeps the state of the entire state sync operation.
@@ -162,6 +165,23 @@ func (t *stateSync) Sync(ctx context.Context) error {
 	return eg.Wait()
 }
 
+// UpdateSyncTarget is not supported for this syncer.
+func (*stateSync) UpdateSyncTarget(message.Syncable) error {
+	return errDynamicSyncerNotSupported
+}
+
+// Finalize assures all data matches the expected state after a sync.
+// This may block while resolving in-flight data.
+func (t *stateSync) Finalize(_ context.Context, summary message.Syncable) error {
+	if t.root != summary.GetBlockRoot() {
+		return fmt.Errorf("finalizing sync with unexpected root: local %s, expected %s", t.root, summary.GetBlockRoot())
+	}
+
+	// The triedb should have the root available after syncing.
+	_, err := t.trieDB.Reader(t.root)
+	return err
+}
+
 // onStorageTrieFinished is called after a storage trie finishes syncing.
 func (t *stateSync) onStorageTrieFinished(root common.Hash) error {
 	<-t.triesInProgressSem // allow another trie to start (release the semaphore)
diff --git a/sync/types.go b/sync/types.go
index d6e9005b06..7a07e10d56 100644
--- a/sync/types.go
+++ b/sync/types.go
@@ -22,6 +22,14 @@ type Syncer interface {
 	// The sync will respect context cancellation.
 	Sync(ctx context.Context) error
 
+	// UpdateSyncTarget updates the target summary to sync to.
+	// If this is not implemented on the syncer, it should return an error.
+	UpdateSyncTarget(summary message.Syncable) error
+
+	// Finalize assures all data matches the expected state after a sync.
+	// This may block while resolving in-flight data.
+	Finalize(ctx context.Context, summary message.Syncable) error
+
 	// Name returns a human-readable name for this syncer implementation.
 	Name() string