Petroleum-based polyethylene (PE) plastic was widely used as mulch film and caused severe environmental issue, the purpose of this work was to fabricate a biodegradable mulch film (BMF) using waste milk. Firstly, waste milk was treated by potassium persulfate (PS)/KOH to obtain product rich in nutritional polymers (fulvic/humic-like acids) and K+. The product was used as the main substrate to fabricate multinutrient slow-release biodegradable mulch film (HPBMF) by mixing with gelatin, tributyl citrate, ZnO, and (NH4)2SO4. Therein, polymers in product could crosslink with gelatin to form interpenetrating network structure through hydrogen bonding. The as-prepared HPBMF showed good water resistance as well as mechanical properties including stiffness and flexibility. Owing to observed excellent heat/water retention and nutrition slow-release behavior, HPBMF could effectively increase the yields of chickweeds by 225.9 % and 68 % compared with Blank and PE film (PEF). After use, residual fragments further showed significant fertilization effect. Notably, the HPBMF could be degraded in 3–4 months during application, well matching crop season. Attractively, HPBMF had a lower comprehensive cost than PEF and polylactic acid mulch film. Overall, this work provided a “three birds with one stone” approach to realize plastic pollution mitigation, food waste recycling, and nutrition sustainable supply simultaneously.