Wireless body area networks (WBANs) are usually used to collect and monitor health-related information for both critical and non-critical patients. However, the traditional WBAN communication framework is unable to guarantee the successful delivery of critical information due to a lack of administrative control and priority support for emergency data. To overcome these issues, this paper proposes a novel software-defined networking (SDN)-based WBAN (SDWBAN) framework for application-specific traffic management. An application classification algorithm and a packet flow mechanism are developed by incorporating SDN principles with WBAN to effectively manage complex and critical traffic in the network. Furthermore, a Sector-Based Distance (SBD) protocol is designed and utilized to facilitate the SDWBAN communication framework. Finally, the proposed SDWBAN framework is evaluated through the CASTALIA simulator in terms of Packet Delivery Ratio (PDR) and latency. The experimental outcomes show that the proposed system achieves high throughput and low latency for emergency traffic in SDWBANs.