A field experiment was conducted during October 2020–January 2021 at Pandit Jawaharlal Nehru College of Agriculture and Research Institute, Karaikal, Puducherry to study the effect of different seeding rates of [Sesbania bispinosa (Jacq.) W. Wight] (Sesbania) in rice co-culture along with suitable post-emergence herbicides for brown manuring on crop productivity and energetics in wet seeded rice (Oryza sativa L.). The experiment consisted of 10 treatments, viz. T1 ,Sesbania seeding rate for brown manuring (BM) @15 kg/ha with 2,4-D 0.5 kg/ha; T2 , Sesbania seeding rate for BM @20 kg/ha with 2,4-D 0.5 kg/ha; T3 , Sesbania seeding rate for BM @25 kg/ha with 2,4-D 0.5 kg/ha; T4 , Sesbania seeding rate for BM @15 kg/ha with bispyribac sodium 25 g/ha; T5 , Sesbania seeding rate for BM @20 kg/ha with bispyribac sodium 25 g/ha; T6 , Sesbania seeding rate for BM @25 kg/ha with bispyribac sodium 25 g/ha; T7 , rice alone with 2,4-D 0.5 kg/ha; T8 , rice alone with bispyribac sodium 25 g/ha; T9 , hand weeding twice at 20 and 40 DAS (days after sowing); T10, unweeded control in a randomized block design (RBD) with three replications. Sesbania seeding rate for brown manuring (BM) @25 kg/ha + 2,4-D 0.5 kg/ha recorded significantly lower total weed density (73.3 no./m2) and weed dry weight (37.0 g/m2). Significantly higher crop growth rate (CGR) (528.2 g/m2 /day), plant height (132.8 cm) and rice yield (4823 kg/ha) were observed under Sesbania seeding rate for BM @25 kg/ha + 2,4-D 0.5 kg/ha which was comparable with Sesbania seeding rate for BM @25 kg/ha + bispyribac sodium 25 g/ha but superior to treatments without BM and eventually resulted in higher energy productivity (0.59 to 0.60 kg/MJ), energy profitability (7.74 to 7.77 kg/MJ) and the energy use efficiency (8.74 to 8.77). Thus, Sesbania seeding rate @25 kg/ha along with spraying either 2,4-D 0.5 kg/ha or bispyribac sodium 25 g/ha for brown manuring could be recommended in wet seeded rice.