In this work, we propose an energy-efficient HTTP adaptive streaming for high-quality video over heterogeneous networks (HetNets). To support high-quality video and overcome the limitations of a single network, the proposed system downloads the video segments by concurrently using the HetNets. In the proposed system, the segment bitrate, number of requested segments, network sleep time, and size of requested data through each wireless network are determined adaptively to provide seamless high-quality video streaming in an energy and cost efficient way. The proposed system is fully implemented in an Android-based mobile device and tested in an actual wireless network environments.