In this experimental study, the mechanical and adhesion properties of several hydraulic lime mortars incorporating graphene oxide (GO)-based nanomaterials were evaluated. Four different composite mortar samples were prepared by adding different percentages of GO-based powders (functionalized), i.e., 1 wt.% GO, 5 wt.% GO, 5wt.% GO-Ag-GO-Fly ash, and 5 wt.% GO-ZnO-GO-TiO2 into the reference mortar sample. The mortar specimens were analyzed through mechanical tests, FT-IR, and SEM. The behavior of selected mortars exposed to chemical attacks was also investigated. The results indicate that the addition of the functionalized GO-based powders leads to a significant improvement in the mortar’s adhesion to the brick substrate (up to 80%) compared to the reference sample, especially in the case of the hydraulic lime mortar incorporating the mixture of GO-Ag and GO-Fly ash, which also showed good resistance to chemical attacks.