AbstractPolyethylene (PE) film mulching (PM) contributes to the increase of crop yields and farmer incomes at the expense of environment. We performed a 2‐yr field experiment to evaluate the possibility of replacement of PM with poly(butylene‐adipate‐co‐terephthalate)‐based biodegradable film mulching (BM) for winter potato (Solanum tuberosum L.) in the south of China. Both PM and BM treatments showed higher soil temperature and water content than no mulching (NM), and there was no significant difference between PM and BM before 60 d after sowing (DAS). Because of the breakdown of biodegradable film, reduced soil temperature and water content were observed in the BM treatment when compared to PM after 60 DAS, whereas no significant difference was observed in potato yield as well as marketable yield between PM and BM treatments, leading to higher water use efficiency in PM than BM. The net revenues of treatments BM and PM were increased by $1,015 and $1,720 ha−1 in growing season 2015–2016, and $967 and $1,295 ha−1 in 2016–2017, respectively, compared to NM. The PE film was barely degraded, whereas biodegradable film residue was reduced to an extremely low level with less than 5 kg ha−1 on field at 330 DAS. Therefore, BM is a viable and eco‐friendly alternative to PM for increasing yield of winter potato in the south of China.