This study presents an experimental investigation into the multifunctional properties of lime-based mortars enhanced with carbon nanotubes (CNTs) and carbon microfibers (CMFs), aiming to develop self-sensing materials for the structural rehabilitation of culturally and historically significant buildings. The research focuses on the electrical and electromechanical behavior of mortars with varying filler dosages to evaluate their self-monitoring capabilities. Mechanical loading tests, supported by Digital Image Correlation (DIC) technology, were conducted to assess the materials’ ability to detect crack initiation and propagation through changes in electrical resistivity. The incorporation of CNTs and CMFs imparts conductivity and strain sensitivity to the otherwise non-conductive lime matrix, enabling real-time damage detection. The study analyzes the effects of filler content on percolation threshold, piezoresistive response, and mechanical performance to identify optimal formulations that balance structural integrity and sensing functionality. The ultimate goal is to create a restoration material that not only strengthens masonry structures but also enables continuous health monitoring—particularly valuable during seismic events. This approach contributes to more resilient and informed conservation practices by embedding smart sensing capabilities directly into repair materials.