Bang Khun Thian (Thai: บางขุนเทียน, pronounced [bāːŋ kʰǔn tʰīan]) is one of the 50 districts (khet) of Bangkok, Thailand.

Administrative units in the newly combined capital province were renamed from amphoe and tambon to "district" (khet) and "sub-district" (khwaeng).

The industry is jeopardised by coastal erosion—the shoreline has retreated more than a kilometre since 1952—and since 2009, wastewater pollution has negatively impacted cultivation and farmer incomes have declined by 30–90 percent.

The missing numbers 1, 2, 3, 4 and 6 belong to the sub-districts which were split off to form Chom Thong and Bang Bon districts.

[4] Besides, Bang Khun Thian's mangrove forests are also the habitat for the last group of smooth-coated otters (Lutrogale perspicillata, Thai นากใหญ่ขนเรียบ) in Bangkok.