There are a limited number of experimental results available on the retrofit of prestressed concrete structural elements. In addition, there is a lack of analytical models dealing with the flexural performance of such elements. This study addresses the latter problem by presenting a methodology for analysis and design of prestressed concrete flexural elements strengthened with externally bonded, fiber reinforced composites. The method provides systematic suggestions on the analysis and design of strengthened prestressed concrete beams with both bonded and unbonded tendons. The method can be used to determine the flexural capacity and to compute stresses and strains in concrete, tendons, and externally bonded fiber reinforcement. Compared to existing experimental data on carbon strengthened beams, the model provides very good prediction of the flexural performance of strengthened prestressed beams. The equations are also applicable to other fiber types including glass, steel, and aramid.