Mustard has emerged as a vital oilseed crop due to its favourable adaptability to various climatic conditions, its significance as a cooking medium in human diets, and its diverse industrial applications stemming from both its primary and by-products. Because of its low cultivation costs and high market value, mustard can thrive in conditions of water scarcity and poor soil fertility, making it an attractive alternative for farmers, particularly in the Rabi season, as a substitute for wheat. Recognizing the crop's importance, a study was conducted to analyze the economic of mustard production in proportionate Lakhimpur district, Uttar Pradesh. Seventy respondents were selected using a purposive cum random sampling method from seven villages within the Kumbhi block. Primary data was collected through personal interviews based on a pre-structured schedule. The analysis employed both tabular and functional methods to derive conclusions. Respondents were classified into marginal, small, and large farms. It was observed that cultivation costs increased with farm size, with the highest production cost for large farms amounting to Rs.51411.71 per hectare. The largest expense in mustard cultivation was attributed to manure and fertilizer, which accounted for Rs.5450.28 per hectare, while the overall cost of cultivation averaged Rs. 44,835.53 per hectare. On average, the gross income was recorded at Rs. 121711.30, resulting in a net income of Rs. 76875.58. Large farms reported the highest gross income at Rs. 141022.60. The overall input-output ratio for mustard crop was calculated as 1:2.70 ultimately, mustard cultivation was determined to be profitable, with potential for increased profits per unit of time and area, provided that production and marketing constraints are addressed.