Under changing agroecological conditions, identification of high-yielding genotypes and imparting drought resilience in wheat through physiological adjustments are imperative for sustained wheat productivity and to ensure food security. In this study, different doses of foliar-applied potassium (K), including 2% (8.98 g K per liter of water), 4% (17.96 g K per liter of water), and 6% (26.94 g K per liter of water) using K2SO4 (45% elemental K) were tested for growth parameters (length, fresh and dry weights of root and shoot), photosynthetic pigments, and antioxidant (ascorbate peroxidase APX, catalase CAT, peroxidase POD, and superoxide dismutase SOD) responses of promising wheat cultivars (Akbar and Ghazi) during the tillering stage under DS (40% of field capacity). The results revealed that foliar-applied K at 6% concentration was consistently superior, especially for the Akbar cultivar, by recording 75%, 57%, and 50% greater root length, root fresh and dry weights, respectively, than the control. The same combination (Akbar cultivar receiving 6% K) also markedly improved shoot length (42%), fresh weight (31%), and dry weight (66%) compared to the control. Regarding photosynthetic pigments, 6% K improved chlorophyll a (93%), chlorophyll b (51%), total chlorophyll (66%), and carotenoids compared to the control treatment (no K supplementation), indicating improved photosynthetic efficiency and enhanced plant vitality. Moreover, this treatment also enhanced the activity of APX (77%), CAT (107%), POD (101%), and SOD (43%) in the Akbar cultivar compared to the control. Based on the findings of this study, foliar application of K at 6% concentration may be recommended as a promising strategy to mitigate the deleterious effects of drought by enhancing the biosynthesis of photosynthetic pigments and antioxidants, particularly in drought-tolerant cultivars of wheat.