This paper has described how the issue of the rehabilitation of damaged structures has attracted the attention of researchers in order to resolve the undesired problems caused by increased traffic loads, corrosion, or impact damage. Appropriate methods are therefore essential for extending the lifespan of the structures and the application of carbon fiber reinforced polymer (CFRP) sheets has been reported as a promising and viable solution with many advantages such as increased flexural strength, and improved serviceability and durability. CFRP sheets may be used more efficiently by applying prestress. For this effective strengthening application, the method of prestressing CFRP sheets and its feasibility are important parameters that need further investigation. This paper investigates the applicability of a prestressing system on large-scale prestressed concrete beams (3.3 m span) tested under static loading. Nonlinear finite element analysis is conducted to predict the behavior of tested beams, including a parametric study to investigate the contribution of different prestress levels in the CFRP sheets to the flexural behavior of strengthened beams.