This study aimed to identify a suitable drying condition for sweet potato leaves and evaluate the use of the resulting powder in nutrient-dense rice-based snack cakes. Sweet potato leaves were dried by convection and heat-pump methods at (35, 45, and 55) °C, followed by physicochemical, nutritional, antioxidant, texture, and sensory analyses. Heat-pump drying at 45 °C provided the best overall performance, with 14.55% recovery yield, 7.35% moisture, and the highest β-carotene content (141.83 mg/kg), while maintaining high dietary fiber levels. Increasing sweet potato leaf powder from 30% to 50% improved protein, dietary fiber, β-carotene, total polyphenols, and antioxidant activity. The 5:5 rice flour-to-leaf powder formulation achieved the highest protein (10.22 g/100 g), total dietary fiber (16.71 g/100 g), and overall liking (7.60/9). The present study provided an integrated drying-product formulation approach for valorizing sweet potato leaf by-products into acceptable, nutrient-dense snacks.