Due to the construction method used, the use of conventional rebar is impractical for roller-compacted concrete (RCC) pavement applications, and the use of discrete fibers seems to be the best alternative to this problem. Among the available types, synthetic fibers are commonly employed in pavement applications, due to their advantages such as ease of handling, cost efficiency, and corrosion-free nature. However, studies that numerically examined the extent of synthetic fiber contribution to the mechanical properties and structural requirements of RCC pavements are very limited. To fill this gap in the literature, an experimental study was conducted to examine the effects of synthetic fibers on the fresh and hardened-state properties of RCC. Then, using the material parameters obtained in this study and retrieved (to cover the effect of different material compositions and synthetic fiber types) from the literature, thickness design for a sample pavement was conducted for plain and fiber-reinforced concrete mixtures, to determine the effect of different material compositions and fiber types on the thickness requirement of RCC pavements. Based on the results of the conducted experiments, the amount of change in the fresh- and hardened-state performance of RCC mixtures due to the addition of synthetic fibers were presented. Thickness design results showed that the contribution of fibers may vary in RCC mixtures depending on the type and amount of fibers used, and the properties of RCC mixture in which they are used. For the type and amount of fibers considered in this study, up to 25% reduction in required thickness was observed for synthetic fiber-reinforced RCC mixtures.