<p>This study aims to develop predictive models to estimate the interfacial bond strength between fibre and matrix, supporting the design and optimization of fibre-reinforced cementitious composites (FRCCs). The effects of w/c ratio, fibre type, embedded length, and nano-silica content were systematically evaluated using glass, polypropylene, steel, and raffia fibres. Cementitious mixtures with w/c ratios of 0.4, 0.5, and 0.6 and nano-silica dosages from 0 to 3.5% were prepared. Single fibre pull-out tests measured bond performance, while Atomic Force Microscopy (AFM) quantified fibre surface roughness and Field Emission Scanning Electron Microscopy (FESEM) elucidated microstructural features at the Interfacial Transition Zone (ITZ). Results revealed significant dependencies of bond strength on w/c ratio and nano-silica content. Glass fibres exhibited optimal equivalent bond strength at 0.6 w/c, whereas polypropylene, steel, and raffia fibres peaked at 0.4 w/c. Optimal nano-silica dosages varied by fibre type: 3.5% for glass at 0.6 w/c, 1.5% for polypropylene at 0.4 w/c, and 3.5% for steel and raffia at 0.5 w/c. Incorporation of nano-silica also enhanced matrix compressive strength. A nonlinear regression model based on experimental data showed excellent predictive capability (R² = 0.9144) for bond strength. These insights contribute to the design of durable, high-performance FRCCs for sustainable construction applications.</p>