This paper investigates the bond performance of a hybrid lap-spliced connection of glass fiber reinforced polymer (GFRP) bars and stainless steel bars in concrete. To gain a comprehensive understanding, micro-level and macro-level mechanical studies are conducted. First, the microstructural characterization of GFRP bars is performed to comprehend the specific material features. Then, cantilever tests are conducted to identify the optimal direction of bar grooves, which is pre-cut by a machine, and to place the distributed fiber optical sensor (DFOS). Subsequently, four-point flexural tests are carried out on eight large-scale specimens to investigate the influence of lap-spliced length and type on the specimen responses. The DFOSs are employed in the grooves of lap-spliced GFRP and stainless steel bars to characterize their bond behaviors. The findings indicate a significant enhancement in load capacity, with an increase of approximately 10 kN for every 100 mm increase in the lap-spliced length. Furthermore, the incorporation of a hybrid connection, combining GFRP and stainless steel bars, demonstrates a slight improvement of 5 kN in load capacity over the pure lap-spliced connection of stainless steel bars. Additionally, detailed investigations are conducted on the strain distributions in the lap-spliced bars.