Barley (Hordeum vulgare L.) is an important cereal crop cultivated in diverse agroecological regions, while yield stability under rainfed conditions remains a major challenge due to environmental variability and limited water availability. This research evaluated twenty barley genotypes to assess phenotypic diversity, trait correlations, and genotype classification based on agronomic and morphometric traits via Field trial under the Moghan (39°38′ N, 47°54′ E) conditions under rainfed conditions characterized by an average annual rainfall of 335 mm. Ten traits were recorded, including plant height (PH), spike height (SH), number of tillers per plant (NTP), number of fertile tillers (NFT), straw weight (SW), biomass weight (BW), number of grains per plant (NGP), grain yield per plant (GYP), grain yield (GY), and thousand-grain weight (TGW). Correlation analysis demonstrated that GY was positively associated with BW and TGW, indicating that both vegetative growth and grain size are key contributors to yield, while a significant negative correlation was observed between spike height (SH) and thousand-grain weight (TGW), indicating a trade-off between spike architectural traits and grain size development. Genotypic clustering divided the barley genotypes into three distinct groups. Cluster-I comprised genotypes with high grain yield and favorable per-plant productivity, Cluster-II included low-performing genotypes with limited biomass and yield potential, and Cluster-III consisted of tall, biomass-rich genotypes with competitive grain yield. Thus, Cluster-III genotypes offer potential for enhancing biomass production, plant vigor, and morphological traits associated with environmental adaptation such as plant height and spike architecture. Genotypes from Cluster-I may be prioritized for direct yield improvement, whereas Cluster-III genotypes offer potential for enhancing biomass production, plant vigor, and adaptive traits. This research provides a framework for genotype selection and supports breeding strategies aimed at improving yield in rainfed barley production systems.