Exploration of high-performance Pt-free electrochemical catalysts for hydrogen evolution reaction (HER) mainly depends on the catalyst design and system construction. Here, a unique flexible HER catalyst of few-layered MoSe2 nanosheets perpendicularly grown on 3D elastic carbonized melamine foam (CMF) is fabricated through a solvothermal reaction. The rationally designed 3D hierarchical CMF/MoSe2 composite foam with conductive 3D networks and fully exposed MoSe2 active edges can provide efficient and rapid pathways for ion and electron transport, thus delivering largely enhanced HER catalytic performance with a low onset potential (-0.071 V vs. RHE), small tafel slop (49.3 mV dec(-1)), as well as excellent long-term stability. This research may pave the way for the development of flexible, lightweight, and low-cost catalysts for high-performance HER. (C) 2018 Elsevier Ltd. All rights reserved.