QoS based uplink data buffering while TTI bundling is enabled by a wireless user equipment (UE) device. The UE may establish a packet-switched connection with a network via a wireless link. The UE may receive, at a media access control (MAC) layer, an indication to enable TTI bundling. The UE may selectively buffer uplink data at an application layer based on the indication to enable TTI bundling. The uplink data may be buffered selectively based on Quality of Service (QoS) considerations. Uplink transmissions may subsequently be performed using TTI bundling.