This paper presents a message queue telemetry transport (MQTT) broker with priority support for emergency events in the Internet of Things (IoT), which is abbreviated p-MQTT. To support the timely and reliable message delivery of emergency events, the p-MQTT classifies the published messages coming into the broker server and controls their priority according to the classification results. To this end, the p-MQTT consists of three components: virtual queue, classification, and priority control. The virtual queue stores the published messages separately according to their type, for which the p-MQTT broker server maintains three virtual queues: Urgent, Critical, and Normal. The classification component classifies the published messages into the three types mentioned above by checking the message type field in the published message header and stores the messages in the appropriate virtual queue. Finally, the priority control assigns a forwarding priority to each virtual queue and adjusts the quality-of-service (QoS) level of the messages within each virtual queue accordingly. To verify its effectiveness, we conduct an experimental implementation of the p-MQTT. The results show that the p-MQTT achieves better performance in emergency events than the existing MQTT.