Methods, systems, and computer readable media for priority routing of Diameter messages are disclosed. In some examples, a method includes determining a Diameter Routing Message Priority (DRMP) priority value for a Diameter message. The method includes marking each of one or more Internet protocol (IP) packets carrying the Diameter message with an IP quality of service (QoS) value for the Diameter message based on the DRMP priority value. The method includes sending the one or more IP packets carrying the Diameter message to a destination Diameter node by way of an IP router on a data communications network providing quality of service using IP QoS values.