The current study, "Economic Analysis of Cost of Production and Profitability of Watermelon in Thiruvallur District of Tamil Nadu in India," was conducted from 2022 to 2023. 100 farmers from the study area were chosen at random to participate in the study. Analyzing the costs, returns, profitability, marketing, and production of watermelons in the study area were the study's primary goals. 100% of the farmers used drip irrigation to grow watermelons and sowed seeds during the rabi season. The majority of farmers in the study area employed inputs that were above what was advised for watermelon cultivation. Pre-structured interview schedules were used to collect the data. The survey indicated that marginal farmers, small and semi-medium farmers, and medium farmers, respectively, spent Rs 155691.8, Rs 154302.5, Rs 149897, and Rs 148131.5 per hectare on watermelon farming on average. On marginal, small, semi-medium, and medium farms, the input-output ratio concerning cost C was (1:1.36), (1:1.39), (1:1.41), and (1:1.44), respectively. The cost of production lowers as farm size grows.