Maize (Zea mays L.) is a globally important cereal crop, serving as a staple food, livestock feed, and industrial raw material, with immense economic and agricultural significance. However, maize productivity in Nepal remains constrained by limited genetic diversity, suboptimal genotype selection, and environmental variability, leading to inconsistent yields. To address this challenge, evaluating diverse maize genotypes under local conditions is essential for identifying high-yielding, stress-tolerance, and adaptable varieties. Therefore, this study was conducted in a farmer-managed agricultural field in Itahari, Sunsari, Nepal, to evaluate the genetic diversity and agronomic performance of twenty-four maize genotypes, aiming to identify high-yielding and adaptable varieties for sustainable production. The trial utilized a Randomized Complete Block Design (RCBD) with three replications, allowing for precise comparison across genotypes. Significant variations were observed in key vegetative and reproductive traits. RML152/RML96 demonstrated the tallest plant height, suggesting its potential for high biomass production, particularly in silage applications, although it requires careful management to avoid lodging. RH10, with its shorter stature and lower ear placement, showed strong resistance to lodging, making it suitable for regions prone to high winds or mechanical harvesting. RL35-1/RML2001 exhibited the highest number of grains per row, while RML142/RML17 had the highest thousand kernel weight, both indicating strong yield potential. The genotype RL284/RML146 emerged as the top performer, achieving the highest grain yield due to its favorable cob size, grain row count, and efficient nutrient utilization. Based on these findings, RL284/RML146, RL35-1/RML2001, and RML142/RML17 are recommended for cultivation in environments prioritizing high productivity.