A field experiment was conducted at the farm of AICRP-Weed Management, B. A. College of Agriculture, Anand Agricultural University, Anand, Gujarat during two consecutive Kharif (rainy) seasons of the year 2019 and 2020 to study the efficacy of sequential and tank mix application of different herbicides on weeds, seed cotton yield and economics of Bt. cotton. Significantly lower weed density and weed dry weight with higher weed control efficiency (WCE), seed cotton yield and net realization in Bt. cotton could be achieved by either tank mix application of pendimethalin (38.7% CS) 500 g/ha + oxyfluorfen 50 g/ha as pre-emergence (PE) fb tank mix application of pyrithiobac-sodium 62.5 g/ha + quizalofop-ethyl 50 g/ha as post-emergence (PoE) or oxyfluorfen 100 g/ha as PE fb glufosinate ammonium 375 g/ha directed spray as PoE or IC + HW  at 20, 40 and 60 DAS.