diff --git a/pkg/service/backup_routine_handler.go b/pkg/service/backup_routine_handler.go
index 3144454a..9f192313 100644
--- a/pkg/service/backup_routine_handler.go
+++ b/pkg/service/backup_routine_handler.go
@@ -180,10 +180,15 @@ func (h *BackupRoutineHandler) runFullBackupInternal(ctx context.Context, now ti
 
 	h.lastRun.SetFullBackupTime(&now)
 
-	err = h.retentionManager.deleteOldBackups(ctx)
-	if err != nil {
-		return fmt.Errorf("failed to clean up old backups: %w", err)
-	}
+	go func() {
+		// Cleanup old backups asynchronously.
+		// At this moment backup is already completed, but backupJob.isRunning flag is still set,
+		// we don't want to block other backup execution.
+		err = h.retentionManager.deleteOldBackups(ctx)
+		if err != nil {
+			h.logger.Error("failed to clean up old backups", slog.Any("error", err))
+		}
+	}()
 
 	return nil
 }
diff --git a/pkg/service/retention_manager.go b/pkg/service/retention_manager.go
index da927528..3a8b2a0a 100644
--- a/pkg/service/retention_manager.go
+++ b/pkg/service/retention_manager.go
@@ -5,6 +5,7 @@ import (
 	"errors"
 	"fmt"
 	"slices"
+	"sync"
 	"time"
 
 	"github.com/aerospike/aerospike-backup-service/v3/pkg/model"
@@ -18,6 +19,7 @@ type RetentionManager interface {
 }
 
 type RetentionManagerImpl struct {
+	mu          sync.Mutex
 	backend     BackupListReader
 	storage     model.Storage
 	routineName string
@@ -39,6 +41,11 @@ func NewBackupRetentionManager(
 }
 
 func (e *RetentionManagerImpl) deleteOldBackups(ctx context.Context) error {
+	if !e.mu.TryLock() { // If delete operation already in progress, skip this iteration.
+		return nil
+	}
+	defer e.mu.Unlock()
+
 	if e.policy == nil || (e.policy.FullBackups == nil && e.policy.IncrBackups == nil) {
 		return nil // Retention policy is not enabled, do nothing.
 	}