There is shortage of information on land preparation and nitrogen application rate for spearmint production in Ethiopia. Thus, a field experiment was conducted at the research site of Wondo Genet Agricultural Research Center (WGARC), Southern Ethiopia, in 2017/18 cropping season to assess the effect of tillage frequency and nitrogen fertilizer rates on growth, yield and essential oil content of spearmint and to evaluate the economic feasibility of treatments for spearmint production. The treatments were consisted of three tillage frequencies [once at the time of planting; twice (1st ten days before planting and 2nd at the time of planting and thrice (1st twenty days before planting, 2nd ten days before planting and 3rd at the time of planting] and five levels of nitrogen (0, 50, 100, 150 and 200 kg N ha-1). Randomized complete block design in a factorial arrangement with three replications was used. Results showed that main effect of tillage frequency and nitrogen fertilizer rates significantly affected fresh stem weight per hectare (FSWPH) and dry herbage biomass per hectare (DHBPH). The highest (2972.58kg ha-1) FSWPH and highest (2973.58kg ha-1) DHBPH were obtained due to three-time tillage. The 200 kg N ha-1 gave the highest (3022.70 kg ha-1) FSWPH and highest (3023.71kg ha-1) DHBPH of spearmint. Days to flowering, plant height and dry leaf to stem ratio were significantly affected by interaction of tillage frequency and N rates. Three times tillage at 200 kg N ha-1 gave tallest plant (78.97 cm), highest essential oil yield per hectare (57.97 kg ha-1) and delayed days to flowering (94 days) and gave highest (2.67) dry leaf to stem to ratio at 150 kg N ha-1. Fresh leaf to stem ratio and fresh herbage biomass per hectare were significantly affected by interaction of tillage frequency and N rates. The highest (4.40) fresh leaf to stem ratio and the highest (15808.50kg ha-1) fresh herbage biomass per hectare were due to three times tillage at 200 kg N ha-1. The highest (12852.50 kg ha-1) fresh herbage yield per hectare and highest (3113.40 kg ha-1) dry herbage yield per hectare) were obtained at three times tillage when 200kg N ha-1 was used. The highest net benefit (8911.79 Birr ha-1) with marginal rate of return (432.01%) was obtained from three times tillage at N fertilizer rate of 100 kg ha-1. Therefore, based on one season study at WGARC it is possible to say that under Wondo Genet and similar areas the highest and economically feasible herb could be produced using three times tillage and 100 kg N ha1.