diff --git a/Config/config.php b/Config/config.php
index 0894eedc6..cfd0aecb3 100644
--- a/Config/config.php
+++ b/Config/config.php
@@ -757,6 +757,7 @@
                     'custom_item.route.provider',
                     'mautic.custom.model.item',
                     'custom_object.config.provider',
+                    'custom_item.xref.contact.repository',
                 ],
             ],
             'custom_item.post_save.subscriber' => [
diff --git a/EventListener/ContactSubscriber.php b/EventListener/ContactSubscriber.php
index 16e27da98..3a0bf8a3b 100644
--- a/EventListener/ContactSubscriber.php
+++ b/EventListener/ContactSubscriber.php
@@ -7,12 +7,14 @@
 use Doctrine\ORM\EntityManager;
 use Mautic\LeadBundle\Entity\LeadEventLog;
 use Mautic\LeadBundle\Entity\LeadEventLogRepository;
+use Mautic\LeadBundle\Event\LeadMergeEvent;
 use Mautic\LeadBundle\Event\LeadTimelineEvent;
 use Mautic\LeadBundle\LeadEvents;
 use MauticPlugin\CustomObjectsBundle\Exception\NotFoundException;
 use MauticPlugin\CustomObjectsBundle\Model\CustomItemModel;
 use MauticPlugin\CustomObjectsBundle\Provider\ConfigProvider;
 use MauticPlugin\CustomObjectsBundle\Provider\CustomItemRouteProvider;
+use MauticPlugin\CustomObjectsBundle\Repository\CustomItemXrefContactRepository;
 use Symfony\Component\EventDispatcher\EventSubscriberInterface;
 use Symfony\Component\Translation\TranslatorInterface;
 
@@ -43,18 +45,25 @@ class ContactSubscriber implements EventSubscriberInterface
      */
     private $configProvider;
 
+    /**
+     * @var CustomItemXrefContactRepository
+     */
+    private $customItemXrefContactRepository;
+
     public function __construct(
         EntityManager $entityManager,
         TranslatorInterface $translator,
         CustomItemRouteProvider $routeProvider,
         CustomItemModel $customItemModel,
-        ConfigProvider $configProvider
+        ConfigProvider $configProvider,
+        CustomItemXrefContactRepository $customItemXrefContactRepository,
     ) {
         $this->entityManager   = $entityManager;
         $this->translator      = $translator;
         $this->routeProvider   = $routeProvider;
         $this->customItemModel = $customItemModel;
         $this->configProvider  = $configProvider;
+        $this->customItemXrefContactRepository = $customItemXrefContactRepository;
     }
 
     /**
@@ -64,6 +73,7 @@ public static function getSubscribedEvents(): array
     {
         return [
             LeadEvents::TIMELINE_ON_GENERATE => 'onTimelineGenerate',
+            LeadEvents::LEAD_POST_MERGE      => 'onContactMerge',
         ];
     }
 
@@ -99,6 +109,15 @@ public function onTimelineGenerate(LeadTimelineEvent $event): void
         }
     }
 
+    public function onContactMerge(LeadMergeEvent $event): void
+    {
+        if (!$this->configProvider->pluginIsEnabled()) {
+            return;
+        }
+
+        $this->customItemXrefContactRepository->mergeLead($event->getVictor(), $event->getLoser());
+    }
+
     /**
      * @return mixed[]
      */
diff --git a/Repository/CustomItemXrefContactRepository.php b/Repository/CustomItemXrefContactRepository.php
index 8297ed6c8..86be4732d 100644
--- a/Repository/CustomItemXrefContactRepository.php
+++ b/Repository/CustomItemXrefContactRepository.php
@@ -63,4 +63,32 @@ public function getContactIdsLinkedToCustomItem(int $customItemId, int $limit, i
             ->getQuery()
             ->getResult();
     }
+
+    public function mergeLead(Lead $victor, Lead $loser): void
+    {
+        // Move all custom item references to the victor lead, but only if the victor doesn't already have
+        // a reference to the custom item
+        $existingAlias = CustomItemXrefContact::TABLE_ALIAS.'_Check';
+
+        $this->createQueryBuilder(CustomItemXrefContact::TABLE_ALIAS)
+            ->update()
+            ->set(CustomItemXrefContact::TABLE_ALIAS.'.contact', ':victor')
+            ->where(CustomItemXrefContact::TABLE_ALIAS.'.contact = :loser')
+            ->andWhere(
+                $this->createQueryBuilder(CustomItemXrefContact::TABLE_ALIAS)
+                    ->expr()
+                    ->notIn(
+                        CustomItemXrefContact::TABLE_ALIAS.'.customItem',
+                        $this->createQueryBuilder($existingAlias)
+                            ->select('IDENTITY('.$existingAlias.'.customItem)')
+                            ->where($existingAlias.'.contact = :victor')
+                            ->getDQL()
+                    )
+            )
+            ->setParameter('victor', $victor->getId())
+            ->setParameter('loser', $loser->getId())
+            ->getQuery()
+            ->execute();
+
+    }
 }