A simple hybrid system is constructed using CdS as photocatalyst and transition metal phosphides as cocatalysts for selectively photocatalytic formic acid decomposition under visible light irradiation at room temperature. By adjusting FA decomposition conditions, different products of H2, CO, or syngas can be obtained according to different demands. With the assistance of bimetallic phosphides as cocatalysts, the H2 and CO production efficiencies can reach up to 138.3 and 116.1 μmol mg−1 h−1 at pH = 1.5 and 9.2, respectively. At pH = 4.4, the syngas efficiency can reach up to 306.9 μmol mg−1 h−1, including 101.4 μmol mg−1 h−1 H2 and 205.5 μmol mg−1 h−1 CO. Moreover, the present heterogeneous system also exhibits excellent photocatalytic stability and still keeps high rates after the five‐cycle reaction, indicating its potential application value.