Tomato (Solanum lycopersicum L.) production is highly influenced by soil fertility management and the efficiency of assimilate distribution within the plant. Thus, this study evaluated the source–sink relationship on the growth and yield parameters of tomato as influenced by organic and inorganic fertilizers. Specifically, the study aimed to: assess the effects of organic and inorganic fertilizers on the vegetative growth parameters of tomato, and determine the influence of fertilizer sources on the yield and yield components of tomato. The experiment was conducted using a randomized complete block design (RCBD) with three replications. Treatments consisted of organic fertilizer (cow dung), inorganic fertilizer (NPK 15:15:15 and Miracle-Gro), and a control. Data were collected on plant height, number of leaves, leaf area, stem girth, days to flowering, fruit weight, number of fruits per plant, and total yield. Soil and plant samples were analyzed using standard laboratory procedures, while data were subjected to analysis of variance at 5% level of significance. Results showed that fertilizer application significantly influenced vegetative growth and yield parameters of tomato. Plants treated with Miracle-Gro recorded the highest plant height, leaf production, and early flowering, while NPK and cow dung improved fruit weight and soil nutrient status. The combined use of organic and inorganic fertilizers enhanced nutrient availability and improved the source–sink efficiency of tomato plants. The study concludes that integrated nutrient management improves tomato growth and productivity and contributes to sustainable soil fertility management.