Onion (Allium cepa L.) is a widely grown vegetable crop in India. Onion production is severely affected by the weed menace which hampers onion growth and yield. A study was conducted at Birsa Agricultural University, Ranchi during 2018 to identify the best feasible method for weed management in onion. Treatments tested include: plastic mulch, available weed mulch at 6t/ha, paddy straw mulch at 7 t/ha, cover crop, pre-emergence application (PE) of oxyfluorfen 0.5 kg/ha, pendimethalin 1 kg/ha PE, mechanical weeding, hand weeding and weedy check. Amongst the treatments, black plastic mulch was found to be most effective in controlling weeds with minimum weed density and biomass, weed index (%) and highest weed control efficiency (%) as compared to other treatments. Onion grown with black plastic mulch showed better onion growth in terms of maximum plant height, number of leaves/plant, neck thickness and maximum onion yield attributes like average bulb weight, average bulb diameter and bulb yield. However, pendimethalin PE recorded highest net returns and B:C as it was cost effective.