Drying shrinkage can lead to microcracking and reduced durability, especially when external curing is insufficient. Internal curing effectively addresses this issue by supplying additional internal water that sustains hydration when external curing is inadequate, water to the concrete matrix to sustain hydration, and alleviating strains caused by shrinking. This study investigates the influence of internal curing utilizing water-absorbing polymer balls (WAPB), lightweight aggregate (LWA), and their hybrid complex on the drying shrinkage and flexural strength of concrete. Seven concrete admixtures were developed: two references (Rw, Rair), WAPB, 50% LWA, Hybrid (25% LWA + 5% WAPB) following ACI 211.1, and two fully lightweight concretes (LWAw, LWAair) following ACI 211.2. Flexural strength was tested on 100×100×400 mm prisms (9 per mix) at 28, 60, and 90 days according to ASTM C293. Drying shrinkage was monitored on prisms of the same size per ASTM C157 with a 200 mm gauge length. The results showed that the 50% LWA mixture achieved the greatest reduction in drying shrinkage (67.5×10⁻⁶ at 28 days; 175×10⁻⁶ at 120 days), decreasing strains by approximately 61% at 28 days and 42% at 120 days compared with the reference mix. The Hybrid mix also demonstrated stable long-term behavior with a 14% increase only between 28 and 120 days. The flexural strength slightly decreased in all internally cured combinations relative to the water-cured reference because of increased porosity; however, it remained within acceptable structural limits.