Exploring　noble-metal-free,　highly　active　and　durable　catalysts　is　vital　to　get　to　grips　with　the　energy　and　environmental　issues.　Herein,　we　first　dexterously　design　and　synthesize　a　class　of　ternary　Nb6/CZS/g-CN　photocatalysts　for　the　removal　of　hexavalent　chromium　Cr　(VI)　and　organic　dye　pollutant　(MO)　from　wastewater　under　visible-light　irradiation.　A　heterojunction　Nb6–1/CZS/g-CN　loaded　with　0.01 g　K7HNb6O19　showed　excellent　photocatalytic　performance,　with　the　MO　photodegradation　efficiency　of　94%　in　1 h　and　the　Cr　(VI)　(150 mg/l)　photoreduction　efficiency　as　high　as　91%　in　2 hr.　The　main　active　species　were　deemed　to　be　O2.-.　Additionally,　the　as-prepared　ternary　heterojunction　exhibits　superior　hydrogen　evolution　reaction　(HER)　rate.　A　heterojunction　Nb6–4/CZS/g-CN　loaded　with　0.5 g　K7HNb6O19　exhibited　the　highest　H2　evolution　rate　as　high　as　1777.86 μmol h−1 g−1　under　visible-light　illumination,　which　is　increased　to　5.7　and　2.7　times　that　of　bare　CZS　and　biphase　heterojunction　CZS/g-CN.　These　findings　afford　a　new　class　of　promising　low-cost　photocatalyst　bodying　for　its　huge　potential　value　in　sustainable　energy　development　and　wastewater　treatment.　©　2019　John　Wiley　&　Sons,　Ltd.