Aramid fiber-reinforced polymer (AFRP) tendons, which are inherently corrosion-resistant, can be used to replace steel prestressing strands in bridge girders to enhance bridge sustainability. Despite ongoing experimental research, there is a lack of uniformity and consistency in testing procedures, definitions of material characteristics, and results. Therefore, a robust computational model is needed to perform a refined nonlinear analysis of full-scale AFRP prestressed girders. This paper presents the development of a computational model to numerically evaluate the flexural behavior of an AASHTO (American Association of State Highway and Transportation Officials) I-girder (Type I) prestressed with AFRP tendons in comparison to its conventional prestressing steel counterpart. Numerical results match experimental test data with a high degree of accuracy and reveal that an AASHTO I-girder prestressed with AFRP meets service and strength limit states. Numerical results also show that the deflection equation in ACI 440.4R overestimates the maximum deflection of the AFRP prestressed girder.