Fiber-reinforced cementitious matrix (FRCM) composites can be used to strengthen existing reinforced concrete members in flexure and shear, or to improve their axial behavior through confinement. While numerous experimental, analytical, and numerical investigations regarding the contributions of externally bonded (EB) FRCM composites to the flexural capacity of RC beams can be found in the literature, quite limited work has been done to investigate the shear strength contribution of EB FRCM jackets applied to RC members. In this paper, the contribution provided by an EB FRCM composite to the RC beam shear strength is investigated. Five beams under-reinforced in shear are tested. One is used as control whereas four are strengthened in shear with an EB FRCM comprising a polyparaphenylene benzobisoxazole (PBO) textile embedded within a cement-based mortar. The FRCM is U-wrapped around the beam cross-section. The parameters studied are the number of layers, inclination of textile principal direction (PD) with respect to the beam longitudinal axis, and presence of FRCM anchorages. The results obtained shed light on the role of these parameters on the shear strength contribution provided by the FRCM, contributing to the body of knowledge on this topic.