© 2020 Elsevier B.V. Inspired by waste to energy production, we report construction of dual Z-scheme advanced photocatalyst g-C3N4/Bi4Ti3O12/Bi4O5I2 heterojunction for coupled photocatalytic H2 evolution and degradation of antibiotics with high efficiency. The optimal CTBT-30 i.e (40 %g-C3N4/Bi4Ti3O12)/30 % Bi4O5I2 photocatalyst exhibited an excellent rate of H2 production under visible light (56.2 mmol g−1 h−1) along with simultaneous 87.1 % ofloxacin (OFL) removal. The H2 production rate is manifolds higher than in ultrapure water, sulfadiazine, rhodamine B and higher in hole scavenging triethanolamine. The interfacial intimate coupling with well-matched energy bands, foster the charge separation with effective Z-scheme transfer facilitated by I3−/I− and Bi3+/Bi5+ and redox mediators. The scavenging of majority of holes for direct oxidation or via [rad]OH radical formation leaves photogenerated electrons (at CB of g-C3N4 and Bi4O5I2) free for H2 evolution from H2O. Such work is promising for designing high photo-absorbing heterojunction photocatalysts for dual functionalities of clean energy production and environmental detoxification.