diff --git a/.changelogs/1.1.6/296_fix_validate_node_presence_when_pinning_guests.yml b/.changelogs/1.1.6/296_fix_validate_node_presence_when_pinning_guests.yml
new file mode 100644
index 0000000..3a0782c
--- /dev/null
+++ b/.changelogs/1.1.6/296_fix_validate_node_presence_when_pinning_guests.yml
@@ -0,0 +1,3 @@
+fixed:
+  - Validate for node presence when pinning guests to avoid crashing (@gyptazy). [#296]
+  
\ No newline at end of file
diff --git a/proxlb/models/guests.py b/proxlb/models/guests.py
index 2bf7d61..c3a9fb5 100644
--- a/proxlb/models/guests.py
+++ b/proxlb/models/guests.py
@@ -107,7 +107,7 @@ class Guests:
                     guests['guests'][guest['name']]['affinity_groups'] = Tags.get_affinity_groups(guests['guests'][guest['name']]['tags'])
                     guests['guests'][guest['name']]['anti_affinity_groups'] = Tags.get_anti_affinity_groups(guests['guests'][guest['name']]['tags'])
                     guests['guests'][guest['name']]['ignore'] = Tags.get_ignore(guests['guests'][guest['name']]['tags'])
-                    guests['guests'][guest['name']]['node_relationships'] = Tags.get_node_relationships(guests['guests'][guest['name']]['tags'])
+                    guests['guests'][guest['name']]['node_relationships'] = Tags.get_node_relationships(guests['guests'][guest['name']]['tags'], nodes)
                     guests['guests'][guest['name']]['type'] = 'ct'
 
                     logger.debug(f"Resources of Guest {guest['name']} (type CT) added: {guests['guests'][guest['name']]}")
diff --git a/proxlb/models/tags.py b/proxlb/models/tags.py
index 1317cc7..2bc891a 100644
--- a/proxlb/models/tags.py
+++ b/proxlb/models/tags.py
@@ -12,7 +12,9 @@ __license__ = "GPL-3.0"
 
 import time
 from typing import List
+from typing import Dict, Any
 from utils.logger import SystemdLogger
+from utils.helper import Helper
 
 logger = SystemdLogger()
 
@@ -153,7 +155,7 @@ class Tags:
         return ignore_tag
 
     @staticmethod
-    def get_node_relationships(tags: List[str]) -> str:
+    def get_node_relationships(tags: List[str], nodes: Dict[str, Any]) -> str:
         """
         Get a node relationship tag for a guest from the Proxmox cluster by the API to pin
         a guest to a node.
@@ -163,6 +165,7 @@ class Tags:
 
         Args:
             tags (List): A list holding all defined tags for a given guest.
+            nodes (Dict): A dictionary holding all available nodes in the cluster.
 
         Returns:
             Str: The related hypervisor node name.
@@ -174,7 +177,13 @@ class Tags:
             for tag in tags:
                 if tag.startswith("plb_pin"):
                     node_relationship_tag = tag.replace("plb_pin_", "")
-                    node_relationship_tags.append(node_relationship_tag)
+
+                    # Validate if the node to pin is present in the cluster
+                    if Helper.validate_node_presence(node_relationship_tag, nodes):
+                        logger.info(f"Tag {node_relationship_tag} is valid! Defined node exists in the cluster.")
+                        node_relationship_tags.append(node_relationship_tag)
+                    else:
+                        logger.warning(f"Tag {node_relationship_tag} is invalid! Defined node does not exist in the cluster. Not applying pinning.")
 
         logger.debug("Finished: get_node_relationships.")
         return node_relationship_tags
diff --git a/proxlb/utils/helper.py b/proxlb/utils/helper.py
index 7fff9f1..7bdda17 100644
--- a/proxlb/utils/helper.py
+++ b/proxlb/utils/helper.py
@@ -265,3 +265,27 @@ class Helper:
                 return parts[0], port
             except ValueError:
                 return host_object, 8006
+
+    @staticmethod
+    def validate_node_presence(node: str, nodes: Dict[str, Any]) -> bool:
+        """
+        Validates whether a given node exists in the provided cluster nodes dictionary.
+
+        Args:
+            node (str): The name of the node to validate.
+            nodes (Dict[str, Any]): A dictionary containing cluster information.
+                                    Must include a "nodes" key mapping to a dict of available nodes.
+
+        Returns:
+            bool: True if the node exists in the cluster, False otherwise.
+        """
+        logger.debug("Starting: validate_node_presence.")
+
+        if node in nodes["nodes"].keys():
+            logger.info(f"Node {node} found in cluster. Applying pinning.")
+            logger.debug("Finished: validate_node_presence.")
+            return True
+        else:
+            logger.warning(f"Node {node} not found in cluster. Not applying pinning!")
+            logger.debug("Finished: validate_node_presence.")
+            return False