AbstractReplacing steel reinforcement with glass fiber-reinforced polymer (GFRP) reinforcement is an effective solution to avoid the corrosion problem in precast concrete tunnel-lining (PCTL) segments. In addition, using high-strength concrete (HSC) can improve the durability of concrete in the harsh environment of tunnels. This study pioneers in investigating the structural performance of GFRP-reinforced PCTL segments constructed with HSC by testing four full-scale specimens measuring 3,100 mm in length, 1,500 mm in width, and 250 mm in thickness under a three-point bending load. The investigated parameters included concrete compressive strength [normal-strength concrete (NSC) and HSC], reinforcement ratio (0.48% and 0.90%), and tie configuration (closed ties with U-shaped ties). The results are presented and discussed in terms of cracking behavior, failure mechanism, deflection behavior, strain in reinforcement and concrete, ductility, and deformability. An analytical investigation was carried out to evaluate and modify the existing design provisions (ACI 440.1R-15, CAN/CSA S806-12, CAN/CSA S6-19, and AASHTO 2018) for use in predicting the shear and flexural strength of GFRP-reinforced HSC PCTL segments. The results indicate that using HSC improves the flexural and shear strength of GFRP-reinforced PCTL segments, while it has a minimal effect on the postcracking stiffness and cracking behavior of the specimens. According to the analytical investigation, the procedure presented to modify ACI 440.1R-15 can be used to predict the flexural capacity of GFRP-reinforced HSC PCTL segments with high accuracy. In addition, CAN/CSA S806-12 predicts the shear capacity of HSC-GFRP-reinforced PCTL segments with an error of less than 7.0%.