It remains a challenge to develop efficient and inexpensive catalysts for hydrogen evolution reaction ( HER). Herein, it is the first time to report a core-shell structured amorphous Fe-B alloy coupled with metal Fe nanoclusters as an efficient HER catalyst. The composite was fabricated via the transformation of the FeOOH coating on amorphous Fe-B alloy into metal Fe through a simple photoreduction approach. The Fe nanoclusters loaded on amorphous Fe-B alloy improve the catalytic HER. Thus, the as-prepared composite exhibits much better electrocatalytic and photocatalytic HER activities than single Fe and Fe-B alloy, that is, there is a synergic effect between Fe metal and amorphous Fe-B alloy. The highest apparent quantum yield (AQY) for photocatalytic HER reaches 34% at 470 nm with Eosin Y as a photosensitizer. The composite cocatalyst can be recovered by a magnetic field after the dye-sensitized photocatalytic HER. More interestingly, the electrocatalytic HER activity of Fe-B@Fe-10 in alkaline solution surpasses that of foam Ni used in industrial water electrolysis, and the core-shell composite shows excellent HER performance at high current density. The findings provide new insights to develop efficient and stable noble-metal-free HER catalysts.