One of the most important and well-known crops worldwide is the tomato (Solanum lycopersicum L.). It is an important member of the Solanaceae family and can be easily propagated by seed. A two-factor experiment was executed to determine how different doses of gamma irradiation impact the growth and yield performance of three genotypes of tomatoes, namely, LTS, LT, and BTP. Four levels of gamma irradiation, namely, control (without irradiation), 200 Gy, 250 Gy, and 300 Gy from a ⁶⁰Co source, were applied to the seeds of the three genotypes. The experiment was laid out in a Randomized Complete Block Design (RCBD) with three replications. Data on growth parameters were collected on different days after transplanting, and the yield attributes were recorded at harvest. The LTS genotype treated with 200 Gy gamma irradiation showed superior results for plant height (160.13 cm), number of leaves per plant (161.60), leaf length (20.30 cm), leaf diameter (20.57 cm), fruit weight per plant (3.95 kg), fruit yield per plot (35.55 kg), and yield per hectare (88.88 t). The LT genotype with the 300 Gy treatment showed the greatest number of branches per plant (26.87), the most flower clusters per plant (33.67), and the highest number of fruits per plant (83.67). The BTP with the control treatment did not perform well. The highest yield (77.82 t/ha) was noted at 200 Gy, while the lowest (60.47 t/ha) occurred under the control treatment. In case of genotypes, LTS produced the maximum yield (81.68 t/ha) and BTP the minimum (59.73 t/ha). The best treatment–genotype combination was LTS with 200 Gy (88.88 t/ha), whereas BTP under the control treatment showed the lowest yield (52.02 t/ha). The experimental outcome will be useful for comparative evaluation of the irradiated tomato genotypes in subsequent generations for potential varietal improvement through induced mutation.