It is of great importance to design and fabricate heterojunction photocatalysts to improve photocatalytic performance. In this work, a novel ZIF-67/AgCl/Ag heterojunction photocatalyst was successfully synthesized by a facile chemical etching, deposition–precipitation, light-induced reduction approach. After chemical etching by a AgNO₃ precursor, the crystal size of ZIF-67 decreased remarkably together with the replacement of Co²⁺ in the framework of ZIF-67 by Ag⁺ via surface ion exchange. As a result, optical and electrochemical measurements indicated that the separation efficiency of light-induced electrons and holes obviously increased due to the formation of a ZIF-67/AgCl/Ag heterojunction and the surface plasmon resonance of Ag⁰. Meanwhile, the corresponding kinetic rate constant of ZIF-67/AgCl/Ag was estimated to be 0.1615 min⁻¹, which was 17, 7.76 and 2.67 times as high as that of individual ZIF-67, AgCl and ZIF-67/AgCl, respectively. The ZIF-67/AgCl/Ag photocatalyst also exhibited good stability and reusability in the process of photodegradation. This work demonstrated a high efficiency photocatalyst for providing new sights into the preparation of a highly efficient MOF-based heterojunction photocatalyst and its potential applications in water purification.