Hybrid organic-inorganic perovskites have been pursuing for solar/visible-driven H-2 evolution from hydrohalic acid (HX) splitting, but their inherent structural stability and performance are still challenging. Herein, we report on a stable hybrid perovskite MAPb(I1-xBrx)(3) (x = 0-0.20) obtained by one-pot crystallization in a mixed halide parent solution and its implementation as a newcomer photocatalyst for H-2 evolution in aqueous HX solution. MAPb(I1-xBrx)(3) is demonstrated to be a superior visible-light-driven photocatalyst for H-2 evolution in aqueous HI/HBr solution with no Pt as a cocatalyst. An optimized MAPb(I1-xBrx)(3) (x = 0.10) shows a highest H-2 evolution rate of 1471 mu mol h(-1) g(-1) under visible light (lambda >= 420 nm) illumination, which is (similar to)40 times higher than that of pure MAPbI(3), and the dual-halide perovskite is rather stable showing no obvious decrease in the photocatalytic activity over 60 runs (252 h). The perovskite inherent structural stability is further evidenced by XRD, UV-vis spectra and EDS elemental mapping of MAPb(I1-xBrx)(3) measured after cycled photocatalytic reaction. The solar HI splitting efficiency of MAPb(I1-xBrx)(3) (x = 0.10) is determined as 1.42%. The mechanism behind photocatalytic H-2 evolution enhancement is elucidated by the experimental and computational methods.