An experiment was conducted during Kharif seasons of 2020 and 2021 to test the bio-efficacy of diclosulam 84% WDG (diclosulam) for weed management in Kharif season soybean and its succeeding effect on mustard in Rabi season. The study was conducted at District Seed farm-C unit, Bidhan Chandra Krishi Viswavidyalaya, Kalyani, Nadia, West Bengal. The soybean cultivar ‘Pusa 16’ (duration 110 days) was used. The pre-emergence application (PE) of diclosulam 38.7 g/ha was more effective in managing all predominant grasses, sedges and broad-leaved weeds than other tested herbicides, and recorded 34.81%, 77.1%, 51.9%, 19.2% and 53.79% more primary branches/plant, pods/plant, seeds/pod, test weight and seed yield than the weedy check. It was statistically at par with the hand weeding. Both physico-chemical and biological properties of post-harvest soil remained unaffected by herbicidal treatments. Diclosulam at varied dosages did not cause any adverse effect on germination, plant stand and yield of succeeding mustard. Thus, diclosulam 38.7 g/ha PE can be recommended for effective control of grasses, sedges and broadleaved weeds in soybean under soybean-mustard cropping system.