diff --git a/core/services/llo/cleanup.go b/core/services/llo/cleanup.go
index dab00965809..1bd7207cf2c 100644
--- a/core/services/llo/cleanup.go
+++ b/core/services/llo/cleanup.go
@@ -86,7 +86,7 @@ func (t *transmissionReaper) runLoop(ctx context.Context) {
 			// make a final effort to clear the database that goes into
 			// overtime
 			overtimeCtx, cancel := context.WithTimeout(context.Background(), OvertimeDeleteTimeout)
-			if n, err := t.reapStale(overtimeCtx, TransmissionReaperBatchSize); err != nil {
+			if n, err := t.reap(overtimeCtx, TransmissionReaperBatchSize, "stale"); err != nil {
 				t.lggr.Errorw("Failed to reap stale transmissions on exit", "err", err)
 			} else if n > 0 {
 				t.lggr.Infow("Reaped stale transmissions on exit", "nDeleted", n)
@@ -94,46 +94,45 @@ func (t *transmissionReaper) runLoop(ctx context.Context) {
 			cancel()
 			return
 		case <-ticker.C:
-			// TODO: Could also automatically reap orphaned transmissions
-			// that don't have a job with a matching DON ID (from job
-			// deletion)
-			//
-			// https://smartcontract-it.atlassian.net/browse/MERC-6807
 			// TODO: Should also reap other LLO garbage that can be left
 			// behind e.g. channel definitions etc
-			n, err := t.reapStale(ctx, TransmissionReaperBatchSize)
-			if err != nil {
-				t.lggr.Errorw("Failed to reap", "err", err)
-				continue
-			}
-			if n > 0 {
-				t.lggr.Infow("Reaped stale transmissions", "nDeleted", n)
-			}
+			t.reapAndLog(ctx, TransmissionReaperBatchSize, "stale")
+			t.reapAndLog(ctx, TransmissionReaperBatchSize, "orphaned")
 		}
 	}
 }
 
-func (t *transmissionReaper) reapStale(ctx context.Context, batchSize int) (rowsDeleted int64, err error) {
+func (t *transmissionReaper) reapAndLog(ctx context.Context, batchSize int, reapType string) {
+	n, err := t.reap(ctx, batchSize, reapType)
+	if err != nil {
+		t.lggr.Errorw("Failed to reap", "type", reapType, "err", err)
+		return
+	}
+	if n > 0 {
+		t.lggr.Infow("Reaped transmissions", "type", reapType, "nDeleted", n)
+	}
+}
+
+func (t *transmissionReaper) reap(ctx context.Context, batchSize int, reapType string) (rowsDeleted int64, err error) {
 	for {
 		var res sql.Result
-		res, err = t.ds.ExecContext(ctx, `
-DELETE FROM llo_mercury_transmit_queue AS q
-USING (
-    SELECT transmission_hash 
-    FROM llo_mercury_transmit_queue
-    WHERE inserted_at < $1
-    ORDER BY inserted_at ASC
-    LIMIT $2
-) AS to_delete
-WHERE q.transmission_hash = to_delete.transmission_hash;
-		`, time.Now().Add(-t.maxAge), batchSize)
+		switch reapType {
+		case "stale":
+			res, err = t.reapStale(ctx, batchSize)
+		case "orphaned":
+			res, err = t.reapOrphaned(ctx, batchSize)
+		default:
+			return 0, fmt.Errorf("transmissionReaper: unknown reap type: %s", reapType)
+		}
+
 		if err != nil {
-			return rowsDeleted, fmt.Errorf("transmissionReaper: failed to delete stale transmissions: %w", err)
+			return rowsDeleted, fmt.Errorf("transmissionReaper: failed to delete %s transmissions: %w", reapType, err)
 		}
+
 		var rowsAffected int64
 		rowsAffected, err = res.RowsAffected()
 		if err != nil {
-			return rowsDeleted, fmt.Errorf("transmissionReaper: failed to get rows affected: %w", err)
+			return rowsDeleted, fmt.Errorf("transmissionReaper: failed to get %s rows affected: %w", reapType, err)
 		}
 		if rowsAffected == 0 {
 			break
@@ -142,3 +141,38 @@ WHERE q.transmission_hash = to_delete.transmission_hash;
 	}
 	return rowsDeleted, nil
 }
+
+func (t *transmissionReaper) reapStale(ctx context.Context, batchSize int) (sql.Result, error) {
+	return t.ds.ExecContext(ctx, `
+DELETE FROM llo_mercury_transmit_queue AS q
+USING (
+    SELECT transmission_hash 
+    FROM llo_mercury_transmit_queue
+    WHERE inserted_at < NOW() - ($1 * INTERVAL '1 MICROSECOND')
+    ORDER BY inserted_at ASC
+    LIMIT $2
+) AS to_delete
+WHERE q.transmission_hash = to_delete.transmission_hash;
+`, t.maxAge.Microseconds(), batchSize)
+}
+
+func (t *transmissionReaper) reapOrphaned(ctx context.Context, batchSize int) (sql.Result, error) {
+	return t.ds.ExecContext(ctx, `
+WITH activeDonIds AS (
+    SELECT DISTINCT cast(relay_config->>'lloDonID' as bigint) as don_id
+	FROM ocr2_oracle_specs
+	WHERE 
+		relay_config->>'lloDonID' IS NOT NULL
+		AND relay_config->>'lloDonID' <> ''
+)
+DELETE FROM llo_mercury_transmit_queue as q
+USING (
+    SELECT transmission_hash 
+    FROM llo_mercury_transmit_queue
+    WHERE don_id NOT IN (SELECT don_id FROM activeDonIds)
+    ORDER BY inserted_at ASC
+    LIMIT $1
+) AS to_delete
+WHERE q.transmission_hash = to_delete.transmission_hash;
+`, batchSize)
+}
diff --git a/core/services/llo/cleanup_test.go b/core/services/llo/cleanup_test.go
index f53a6e083f2..f8f19cf2d20 100644
--- a/core/services/llo/cleanup_test.go
+++ b/core/services/llo/cleanup_test.go
@@ -111,7 +111,7 @@ func Test_Cleanup(t *testing.T) {
 	})
 }
 
-func Test_TransmissionReaper(t *testing.T) {
+func Test_StaleTransmissionReaper(t *testing.T) {
 	ds := pgtest.NewSqlxDB(t)
 	lggr := logger.TestLogger(t)
 	tr := &transmissionReaper{ds: ds, lggr: lggr, maxAge: 24 * time.Hour}
@@ -133,13 +133,45 @@ WHERE transmission_hash IN (
 `)
 
 	// test batching
-	d, err := tr.reapStale(ctx, n/3)
+	d, err := tr.reap(ctx, n/3, "stale")
 	require.NoError(t, err)
 	assert.Equal(t, int64(5), d)
 
 	pgtest.MustExec(t, ds, "UPDATE llo_mercury_transmit_queue SET inserted_at = NOW() - INTERVAL '48 hours'")
 
-	d, err = tr.reapStale(ctx, n/3)
+	d, err = tr.reap(ctx, n/3, "stale")
 	require.NoError(t, err)
 	assert.Equal(t, int64(n-5), d)
 }
+
+func Test_OrphanedTransmissionReaper(t *testing.T) {
+	ds := pgtest.NewSqlxDB(t)
+	lggr := logger.TestLogger(t)
+	tr := &transmissionReaper{ds: ds, lggr: lggr, maxAge: 24 * time.Hour}
+	ctx := testutils.Context(t)
+
+	const n = 13
+
+	pgtest.MustExec(t, ds, `
+	INSERT INTO ocr2_oracle_specs (contract_id, p2pv2_bootstrappers, contract_config_confirmations, created_at,
+			updated_at, relay, relay_config, plugin_config, plugin_type, onchain_signing_strategy, allow_no_bootstrappers
+		) VALUES ('0x','{}', 0, NOW(), NOW(), 'evm', '{"chainID": 421614, "lloDonID": 2}', '{"donID": 2}', 'llo', '{}', FALSE);`)
+
+	// add transmissions from a DON not present in ocr2 specs
+	transmissions := makeSampleTransmissions(n)
+	torm := mercurytransmitter.NewORM(ds, 1)
+	err := torm.Insert(testutils.Context(t), transmissions)
+	require.NoError(t, err)
+
+	d, err := tr.reap(ctx, n, "orphaned")
+	require.NoError(t, err)
+	assert.Equal(t, int64(n), d)
+
+	torm2 := mercurytransmitter.NewORM(ds, 2)
+	err = torm2.Insert(testutils.Context(t), transmissions)
+	require.NoError(t, err)
+
+	d, err = tr.reap(ctx, n, "orphaned")
+	require.NoError(t, err)
+	assert.Equal(t, int64(0), d)
+}