diff --git a/netbox/dcim/api/serializers_/device_components.py b/netbox/dcim/api/serializers_/device_components.py
index 6bace5bd7..12133ec65 100644
--- a/netbox/dcim/api/serializers_/device_components.py
+++ b/netbox/dcim/api/serializers_/device_components.py
@@ -210,10 +210,9 @@ class InterfaceSerializer(NetBoxModelSerializer, CabledObjectSerializer, Connect
     )
     count_ipaddresses = serializers.IntegerField(read_only=True)
     count_fhrp_groups = serializers.IntegerField(read_only=True)
-    mac_address = serializers.CharField(
-        allow_null=True,
-        read_only=True
-    )
+    # Maintains backward compatibility with NetBox <v4.2
+    mac_address = serializers.CharField(allow_null=True, read_only=True)
+    primary_mac_address = MACAddressSerializer(nested=True, required=False, allow_null=True)
     mac_addresses = MACAddressSerializer(many=True, nested=True, read_only=True, allow_null=True)
     wwn = serializers.CharField(required=False, default=None, allow_blank=True, allow_null=True)
 
@@ -221,13 +220,13 @@ class InterfaceSerializer(NetBoxModelSerializer, CabledObjectSerializer, Connect
         model = Interface
         fields = [
             'id', 'url', 'display_url', 'display', 'device', 'vdcs', 'module', 'name', 'label', 'type', 'enabled',
-            'parent', 'bridge', 'lag', 'mtu', 'mac_address', 'speed', 'duplex', 'wwn', 'mgmt_only', 'description',
-            'mode', 'rf_role', 'rf_channel', 'poe_mode', 'poe_type', 'rf_channel_frequency', 'rf_channel_width',
-            'tx_power', 'untagged_vlan', 'tagged_vlans', 'qinq_svlan', 'vlan_translation_policy', 'mark_connected',
-            'cable', 'cable_end', 'wireless_link', 'link_peers', 'link_peers_type', 'wireless_lans', 'vrf',
-            'l2vpn_termination', 'connected_endpoints', 'connected_endpoints_type', 'connected_endpoints_reachable',
-            'tags', 'custom_fields', 'created', 'last_updated', 'count_ipaddresses', 'count_fhrp_groups', '_occupied',
-            'mac_addresses',
+            'parent', 'bridge', 'lag', 'mtu', 'mac_address', 'primary_mac_address', 'mac_addresses', 'speed', 'duplex',
+            'wwn', 'mgmt_only', 'description', 'mode', 'rf_role', 'rf_channel', 'poe_mode', 'poe_type',
+            'rf_channel_frequency', 'rf_channel_width', 'tx_power', 'untagged_vlan', 'tagged_vlans', 'qinq_svlan',
+            'vlan_translation_policy', 'mark_connected', 'cable', 'cable_end', 'wireless_link', 'link_peers',
+            'link_peers_type', 'wireless_lans', 'vrf', 'l2vpn_termination', 'connected_endpoints',
+            'connected_endpoints_type', 'connected_endpoints_reachable', 'tags', 'custom_fields', 'created',
+            'last_updated', 'count_ipaddresses', 'count_fhrp_groups', '_occupied',
         ]
         brief_fields = ('id', 'url', 'display', 'device', 'name', 'description', 'cable', '_occupied')
 
diff --git a/netbox/virtualization/api/serializers_/virtualmachines.py b/netbox/virtualization/api/serializers_/virtualmachines.py
index 48ddfaf4e..dfc205b7c 100644
--- a/netbox/virtualization/api/serializers_/virtualmachines.py
+++ b/netbox/virtualization/api/serializers_/virtualmachines.py
@@ -96,19 +96,18 @@ class VMInterfaceSerializer(NetBoxModelSerializer):
     l2vpn_termination = L2VPNTerminationSerializer(nested=True, read_only=True, allow_null=True)
     count_ipaddresses = serializers.IntegerField(read_only=True)
     count_fhrp_groups = serializers.IntegerField(read_only=True)
-    mac_address = serializers.CharField(
-        allow_null=True,
-        read_only=True
-    )
+    # Maintains backward compatibility with NetBox <v4.2
+    mac_address = serializers.CharField(allow_null=True, read_only=True)
+    primary_mac_address = MACAddressSerializer(nested=True, required=False, allow_null=True)
     mac_addresses = MACAddressSerializer(many=True, nested=True, read_only=True, allow_null=True)
 
     class Meta:
         model = VMInterface
         fields = [
             'id', 'url', 'display_url', 'display', 'virtual_machine', 'name', 'enabled', 'parent', 'bridge', 'mtu',
-            'mac_address', 'description', 'mode', 'untagged_vlan', 'tagged_vlans', 'qinq_svlan',
-            'vlan_translation_policy', 'vrf', 'l2vpn_termination', 'tags', 'custom_fields', 'created', 'last_updated',
-            'count_ipaddresses', 'count_fhrp_groups', 'mac_addresses',
+            'mac_address', 'primary_mac_address', 'mac_addresses', 'description', 'mode', 'untagged_vlan',
+            'tagged_vlans', 'qinq_svlan', 'vlan_translation_policy', 'vrf', 'l2vpn_termination', 'tags',
+            'custom_fields', 'created', 'last_updated', 'count_ipaddresses', 'count_fhrp_groups',
         ]
         brief_fields = ('id', 'url', 'display', 'virtual_machine', 'name', 'description')