Systems and methods for Multi-Radio Access Technology (RAT) Carrier Aggregation (MRCA) wireless wide area network (WWAN) assisted wireless local area network (WLAN) discovery, association, and flow switching are disclosed. One system comprises a control signaling module in a wireless device that includes a WWAN radio integrated with a WLAN radio. The control signaling module is configured to communicate WWAN control signaling and WLAN control signaling via a WWAN radio connection of the wireless device. A dynamic flow mapping module is configured to form a flow-mapping table to dynamically map service flows between the WWAN radio and the WLAN radio in the wireless device. A flow routing module is configured to route data packets to one of the WWAN radio and the WLAN radio in the wireless device based on the flow-mapping table to transmit and receive the data packets via the wireless device.