Lentil (Lens culinaris Medik.) is a key legume for semiarid regions, but its productivity is constrained by drought stress. We hypothesized that foliar application of proline and valine could alleviate the negative effects of water deficit and improve the performance of different lentil varieties. A 2-year field study (2022-2023) evaluated four varieties [Sabzpardis (stress-resistant), Bilehsavar, Sepehr (stress-tolerant), and 590 (stress-sensitive)] under full and deficit irrigation, with or without amino acid application. Results showed that deficit irrigation reduced chlorophyll content, plant height, and flower number by 22-28%. Foliar spraying with amino acids, particularly proline, significantly enhanced chlorophyll a (+16%), fertile pods (+39%), 100-seed weight (+9%), and seed yield (+30%) compared with the untreated control. Under deficit irrigation, the seed yield of varieties followed the sequence Sabzpardis > Sepehr > Bilehsavar > 590, demonstrating the superior tolerance of Sabzpardis. However, no clear synergistic advantage was observed for the combined treatment of Sabzpardis with amino acids beyond their individual effects. Overall, these findings indicate that selecting the Sabzpardis variety and applying proline foliar sprays are effective strategies to sustain lentil yield and quality under water-limited conditions.