The use of fiber-reinforced polymer (FRP) materials to enhance the durability of reinforced concrete (RC) structures in demanding conditions has been well-established. However, the incorporation of openings in FRP-reinforced slabs, while offering architectural advantages, poses challenges to maintaining structural integrity. This paper takes a numerical approach using finite element method (FEM) to investigate the performance of concrete one-way slabs with openings reinforced by glass fiber-reinforced polymer (GFRP) bars and strengthened with carbon fiber-reinforced polymer (CFRP) sheets. The study examines two principal influencing factors, including the opening size and position, which considerably affect the load-bearing capacity of slabs and the effectiveness of CFRP strengthening. The findings of this research have practical implications for the design and construction of RC structures with openings, particularly in terms of optimizing the opening layout to ensure structural integrity.