diff --git a/REFERENCE.md b/REFERENCE.md
index b41cb73a..68918020 100644
--- a/REFERENCE.md
+++ b/REFERENCE.md
@@ -3159,6 +3159,8 @@ The following parameters are available in the `keycloak_protocol_mapper` type.
 * [`realm`](#-keycloak_protocol_mapper--realm)
 * [`resource_name`](#-keycloak_protocol_mapper--resource_name)
 * [`type`](#-keycloak_protocol_mapper--type)
+* [`custom_type`](#-keycloak_protocol_mapper--custom_type)
+* [`custom_config`](#-keycloak_protocol_mapper--custom_config)
 
 ##### <a name="-keycloak_protocol_mapper--client_scope"></a>`client_scope`
 
@@ -3189,13 +3191,21 @@ The protocol mapper name. Defaults to `name`.
 
 ##### <a name="-keycloak_protocol_mapper--type"></a>`type`
 
-Valid values: `oidc-usermodel-property-mapper`, `oidc-usermodel-attribute-mapper`, `oidc-full-name-mapper`, `oidc-group-membership-mapper`, `oidc-audience-mapper`, `saml-group-membership-mapper`, `saml-user-property-mapper`, `saml-user-attribute-mapper`, `saml-role-list-mapper`
+Valid values: `oidc-usermodel-property-mapper`, `oidc-usermodel-attribute-mapper`, `oidc-full-name-mapper`, `oidc-group-membership-mapper`, `oidc-audience-mapper`, `saml-group-membership-mapper`, `saml-user-property-mapper`, `saml-user-attribute-mapper`, `saml-role-list-mapper`, `custom`
 
 protocolMapper.
 
 Default is `oidc-usermodel-property-mapper` for `protocol` `openid-connect` and
 `saml-user-property-mapper` for `protocol` `saml`.
 
+##### <a name="-keycloak_protocol_mapper--custom_type"></a>`custom_type`
+
+Custom mapper type if `type` is set to `custom`.
+
+##### <a name="-keycloak_protocol_mapper--custom_config"></a>`custom_config`
+
+Custom mapper config for custom type. Simple hash with key-value pair, which will be converted to JSON.
+
 ### <a name="keycloak_realm"></a>`keycloak_realm`
 
 Manage Keycloak realms
diff --git a/lib/puppet/provider/keycloak_protocol_mapper/kcadm.rb b/lib/puppet/provider/keycloak_protocol_mapper/kcadm.rb
index ee033c9a..915705c8 100644
--- a/lib/puppet/provider/keycloak_protocol_mapper/kcadm.rb
+++ b/lib/puppet/provider/keycloak_protocol_mapper/kcadm.rb
@@ -74,6 +74,12 @@ def self.instances
             protocol_mapper[:single] = d['config']['single'].to_s.to_sym
           end
           protocol_mapper[:multivalued] = d['config']['multivalued'].to_s.to_sym if d['config']['multivalued']
+          unless ['oidc-usermodel-property-mapper', 'oidc-usermodel-attribute-mapper', 'oidc-full-name-mapper', 'oidc-group-membership-mapper', 'oidc-audience-mapper',
+                  'saml-group-membership-mapper', 'saml-user-property-mapper', 'saml-user-attribute-mapper', 'saml-role-list-mapper', 'saml-javascript-mapper'].include?(d['protocolMapper'])
+            protocol_mapper[:type] = 'custom'
+            protocol_mapper[:custom_type] = d['protocolMapper']
+            protocol_mapper[:custom_config] = d['config']
+          end
           protocol_mappers << new(protocol_mapper)
         end
       end
@@ -105,6 +111,10 @@ def create
     data[:protocol] = resource[:protocol]
     data[:protocolMapper] = resource[:type]
     data[:config] = {}
+    if resource[:type] == 'custom'
+      data[:protocolMapper] = resource[:custom_type]
+      data[:config] = resource[:custom_config]
+    end
     if ['oidc-usermodel-property-mapper', 'saml-user-property-mapper', 'saml-user-attribute-mapper', 'oidc-usermodel-attribute-mapper'].include?(resource[:type]) && resource[:user_attribute]
       data[:config][:'user.attribute'] = resource[:user_attribute]
     end
@@ -192,6 +202,10 @@ def flush
       data[:protocol] = resource[:protocol]
       data[:protocolMapper] = resource[:type]
       config = {}
+      if resource[:type] == 'custom'
+        data[:protocolMapper] = resource[:custom_type]
+        config = resource[:custom_config]
+      end
       if ['oidc-usermodel-property-mapper', 'saml-user-property-mapper', 'saml-user-attribute-mapper', 'oidc-usermodel-attribute-mapper'].include?(resource[:type]) && resource[:user_attribute]
         config[:'user.attribute'] = resource[:user_attribute]
       end
diff --git a/lib/puppet/type/keycloak_protocol_mapper.rb b/lib/puppet/type/keycloak_protocol_mapper.rb
index b06dfd71..2e248bfb 100644
--- a/lib/puppet/type/keycloak_protocol_mapper.rb
+++ b/lib/puppet/type/keycloak_protocol_mapper.rb
@@ -67,6 +67,7 @@
       'saml-user-attribute-mapper',
       'saml-role-list-mapper',
       %r{script-.+},
+      'custom',
     )
     defaultto do
       case @resource[:protocol]
@@ -210,6 +211,14 @@
     desc 'included.client.audience Required for `type` of `oidc-audience-mapper`'
   end
 
+  newproperty(:custom_config) do
+    desc 'custom configuration data for `custom` protocolMapper type'
+  end
+
+  newproperty(:custom_type) do
+    desc 'custom protocolMapper type'
+  end
+
   autorequire(:keycloak_client_scope) do
     requires = []
     catalog.resources.each do |resource|
@@ -248,7 +257,8 @@ def self.title_patterns
       'oidc-full-name-mapper',
       'oidc-group-membership-mapper',
       'oidc-audience-mapper',
-      'oidc-usermodel-attribute-mapper'
+      'oidc-usermodel-attribute-mapper',
+      'custom'
     ]
     if self[:protocol] == 'openid-connect' && !openid_connect_types.include?(self[:type]) && self[:type] !~ %r{script-.+}
       raise Puppet::Error, "type #{self[:type]} is not valid for protocol openid-connect"
@@ -273,5 +283,11 @@ def self.title_patterns
     if self[:type] == 'oidc-audience-mapper' && self[:included_client_audience].nil?
       raise Puppet::Error, 'included_client_audience is required for oidc-audience-mapper'
     end
+    if self[:type] == 'custom' && !self[:custom_type]
+      raise Puppet::Error, 'custom_type is required for `custom` protocol mapper type'
+    end
+    if self[:type] == 'custom' && !self[:custom_config]
+      raise Puppet::Error, 'custom_config is required for `custom` protocol mapper type'
+    end
   end
 end