Construction of heterojunction can effectively suppress the swift recombination of photogenerated electrons and holes in photocatalyst. In this study, a II/Z-type Bi₂MoO₆/Ag₂O/Bi₂O₃ heterojunction photocatalyst was synthesized using a solvothermal method combined with calcination. Various techniques were ultilized to examine the composition, morphology and photoelectrochemical properties of the as-prepared materials. The findings revealed that the optimal composition of the composite material was 25%ABOBM (with a mass ratio of Ag₂O/Bi₂O₃ and Bi₂MoO₆ of 1 : 4). Under visible light irradiation, the degradation efficiency of tetracycline (TC) by 25%ABOBM reached 85.6%, which was significantly higher than that of Ag₂O/Bi₂O₃ and Bi₂MoO₆, and maintained its good stability after three cycles of experiments. The enhanced photocatalytic performance of 25%ABOBM is attributed to the formation of heterojunctions and the unique morphologies among Ag₂O, Bi₂O₃ and Bi₂MoO₆. Both h⁺ and ·O₂^- are significant contributors, while ·OH and ¹O₂ have secondary roles in the degradation process of TC, as indicated by free radical capture experiment and electron paramagnetic resonance spectroscopy (EPR). Furthermore, the related photocatalytic mechanisms were explored, and the potential degradation pathways of TC were analyzed using liquid chromatography-mass spectrometry (LC-MS). This study offers a novel approach to the preparation of photocatalysts with dual heterojunctions and demonstrates their application in the degrading organic pollutants.