This paper presents an experimental study to investigate the performance of repaired reinforced concrete (RC) one-way slabs using fiber reinforced cementitious mortar (FRCM). Glass fiber mesh incorporated FRCM (G-FRCM) was used in repairing the damaged RC slabs to sustain the permissible load. Three one-way slabs (900 × 300 × 80 mm) were tested under the three-point bending test. One slab, considered as control specimen, was evaluated until failure. However, the other two slabs were preloaded up to 30% and 50% of the control specimen. The visible cracks in the preloaded slabs were observed. Thereafter, all the preloaded slabs were repaired with G-FRCM externally. The performance of G-FRCM was investigated in terms of ultimate load, bending capacity, load-deflection behavior, and failure mode of repaired specimens. Results showed an increase in ultimate load and bending capacity on all the G-FRCM repaired slabs. Based on the findings, it can be concluded that G-FRCM overlays comprise a very promising solution for the strengthening and repairing one-way RC slabs.