This paper investigates the punching shear behavior of two-way flat slabs reinforced with glass fiber-reinforced polymer (GFRP) bars. A total of 17 full-scale interior slab–column specimens measuring 2500 mm × 2500 mm reinforced with GFRP and steel bars were constructed and tested under concentric loads until failure. The test parameters were: (i) reinforcement type (GFRP and steel) and ratio (0.34% to 1.66%); (ii) slab thickness (200 mm and 350 mm); (iii) column dimensions (300 mm × 300 mm; 450 mm × 450 mm); (iv) concrete strength (30 to 47 MPa); and (v) GFRP compression reinforcement crossing the column cross section. The test results were reported in terms of cracking behavior, deflection, strains in concrete and reinforcement, punching shear capacity, and mode of failure. The test results were also employed to assess the accuracy of the available punching shear capacity equations, including the new punching equation in Canadian Standards CAN/CSA S806-12.