Chinese mustard is an important leafy vegetable, which is grown in about 5% of total vegetable area in major vegetable producing provinces of Cambodia. Production of Chinese mustard is severely hampered by the insect pests especially lepidopteran caterpillars and the flea beetles. Chinese mustard producers predominantly rely on the application of chemical pesticides for management of these pests and produce blemish free produce. In order to reduce the extensive reliance on pesticides, efficacy of biopesticides (Bacillus thuringiensis and Metarhizium anisopliae formulations, and neem extract), either alone and in combination (as an IPM package) against diamondback moth, common armyworm, cabbage webworm and striped flea beetle on Chinese mustard was assessed in three different provinces of Cambodia during 2015–2018. The bio-pesticides reduced the incidence of diamondback moth, common armyworm, cabbage webworm and the damage by striped flea beetle to the levels equivalent to chemical pesticide (abamectin) during trials in 2015 and 2016. Although the yield was significantly higher in bio-pesticide treated plots than untreated plots in 2015, the yield did not differ among the treatments in 2016 trials. Multi-location trials during 2016–2018 confirmed that the performance of the bio-based IPM package was on par with farmers’ practice of calendar-based pesticide application in reducing the damages by target pests, leading to significant yield gains. Hence, the bio-based IPM package can be a better alternative to chemical pesticides in managing the key insect pests on Chinese mustard in Cambodia.