To address the shortage of river sand and the corrosion of steel reinforcement in coastal regions, this study investigates the bond performance between prestressed Glass Fiber Reinforced Polymer (GFRP) bars and Glass Fiber-Steel Composite (GSFCB) bars with Seawater Sea-Sand Concrete (SWSSC). Central pull-out tests were conducted to systematically evaluate the effects of prestress level, bar diameter, anchorage length, and bar type on bond strength, bond–slip behavior, and failure modes. A bond stress–slip constitutive model was developed based on the experimental results. The results indicate that the GFRP bar specimens predominantly exhibited pull-out failure, whereas the GSFCB bar specimens showed either bar rupture or concrete splitting failure. The bond strength decreased significantly under a prestress level of 0.3 times the ultimate tensile strength, but increased slightly at the 0.6 level. Increasing the anchorage length led to a reduction in bond strength, and larger bar diameters were also associated with decreased bond performance. The use of seawater and sea-sand significantly enhanced the bond strength compared to conventional concrete. A segmented bond–slip constitutive model was established, providing a theoretical basis for the design of prestressed FRP-reinforced SWSSC structures.