diff --git a/CHANGELOG.md b/CHANGELOG.md
index 1c9fd986ee..f360b19453 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -48,6 +48,7 @@
 * [ENHANCEMENT] Query Frontend: Rename `time_taken` field to `time_taken_ms` and make it return millisecond count. #7649
 * [ENHANCEMENT] Update prometheus alertmanager version to v0.33.0. #7647
 * [ENHANCEMENT] Querier/Ingester: Detach ingester series from gRPC buffers to reduce heap. #7670
+* [BUGFIX] Compactor: Correct misleading help text for `cortex_compactor_garbage_collected_blocks_total` metric; it counted blocks garbage collected by the syncer, not all blocks marked for deletion. #3610
 * [BUGFIX] Querier: Fix queryWithRetry and labelsWithRetry returning (nil, nil) on cancelled context by propagating ctx.Err(). #7370
 * [BUGFIX] Metrics Helper: Fix non-deterministic bucket order in merged histograms by sorting buckets after map iteration, matching Prometheus client library behavior. #7380
 * [BUGFIX] Distributor: Return HTTP 401 Unauthorized when tenant ID resolution fails in the Prometheus Remote Write 2.0 path. #7389
diff --git a/pkg/compactor/compactor_metrics.go b/pkg/compactor/compactor_metrics.go
index d777ca9e8e..d1dbd3e9cd 100644
--- a/pkg/compactor/compactor_metrics.go
+++ b/pkg/compactor/compactor_metrics.go
@@ -120,7 +120,7 @@ func newCompactorMetricsWithLabels(reg prometheus.Registerer, commonLabels []str
 	// Copied from Thanos, pkg/compact/compact.go.
 	m.syncerGarbageCollectedBlocks = promauto.With(reg).NewCounterVec(prometheus.CounterOpts{
 		Name: "cortex_compactor_garbage_collected_blocks_total",
-		Help: "Total number of blocks marked for deletion by compactor.",
+		Help: "Total number of blocks garbage collected (deleted after being marked) by the compactor syncer.",
 	}, nil)
 	m.syncerGarbageCollections = promauto.With(reg).NewCounterVec(prometheus.CounterOpts{
 		Name: "cortex_compactor_garbage_collection_total",
diff --git a/pkg/compactor/compactor_metrics_test.go b/pkg/compactor/compactor_metrics_test.go
index 0288bbe909..b1c4e41572 100644
--- a/pkg/compactor/compactor_metrics_test.go
+++ b/pkg/compactor/compactor_metrics_test.go
@@ -65,7 +65,7 @@ func TestCompactorMetrics(t *testing.T) {
 			cortex_compactor_blocks_marked_for_deletion_total{reason="compaction",user="aaa"} 144430
 			cortex_compactor_blocks_marked_for_deletion_total{reason="compaction",user="bbb"} 155540
 			cortex_compactor_blocks_marked_for_deletion_total{reason="compaction",user="ccc"} 166650
-			# HELP cortex_compactor_garbage_collected_blocks_total Total number of blocks marked for deletion by compactor.
+			# HELP cortex_compactor_garbage_collected_blocks_total Total number of blocks garbage collected (deleted after being marked) by the compactor syncer.
 			# TYPE cortex_compactor_garbage_collected_blocks_total counter
 			cortex_compactor_garbage_collected_blocks_total 99990
 			# HELP cortex_compactor_garbage_collection_duration_seconds Time it took to perform garbage collection iteration.