Field experiment was conducted at the Instructional Farm of Bidhan Chandra Krishi Vishwavidyalaya, Mohanpur, Nadia, West Bengal, India during Rabi season of 2013-14 and 2014-15 to study the effect of integrated weed management practices on weeds and yield of onion (Allium cepa L.). At early stage of crop growth i.e. at 10 DAT, maximum weed control efficiency (82.57%) was recorded in the treatment of propaquizafop 0.05 kg/ha + oxyfluorfen 0.25 kg/ha (tank mix) as pre-emergence followed by aqueous extract of cucumber (Cucumis sativus L.) 10% 2.5 liter/ha at 1 DAT (72.83%). Weed control efficiency (WCE) was sustained at later stage with 60.98% and 51.96% in these treatments, respectively. While in the later crop growth phase i.e. 25 DAT onwards, two hand weeding at 20 and 40 DAT recorded significantly the lowest weed density, biomass and higher weed control efficiency (83.27, 77.02, 64.23% at 25, 50 and 75 DAT, respectively). Notable increase in growth and yield attributes viz., plant height, chlorophyll content, LAI, DMA, CGR, bulb diameter, bulb length, scales/bulb, bulb yield, biological yield and harvest index were recorded in two hand weeding followed by PE application of propaquizafop + oxyfluorfen fb mechanical weeding (MW) and cucumber aqueous extract 10% fb MW. The net return and B:C ratio was significantly higher with propaquizafop+ oxyfluorfen fb MW and cucumber aqueous extract 10% fb MW due to lesser cost of herbicides usage compared to hand weeding.