Innovative photoresponsive polypropylene (PP) fibers were successfully fabricated via melt spinning through the incorporation of UV-responsive hybrid silica@phosphomolybdate nanomaterials during the fibers production. Firstly, photochromic hybrid nanomaterials were prepared by immobilization of negatively-charged Keggintype phosphomolybdates - PMo12O40 (PMo12) and PMo11VO40 (PMo11V) - onto positively-charged amine-functionalized silica nanoparticles (SiO2 NPs) through electrostatic interactions. The structural and chemical characterization confirmed the SiO2 NPs functionalization with dimethyloctadecyl[3-(trimethoxysilyl) propyl] ammonium chloride (C18) and N-(2-aminoethyl)-3-aminopropyltrimethoxysilane (AEA), and subsequent phosphomolybdate immobilization. The hybrids exhibited UV-responsive properties, changing from yellow-green to blue with good color contrast (Delta E*(ab)= 5.2-25.8) after being UV irradiated for 1 h, due to Mo-VI cations photoreduction to Mo-V. The bleaching process took several days, but could be accelerated by moderate heating (60-110 degrees C). Among the hybrid nanomaterials, the SiO2 NPs functionalized with C18 and PMo12 (SiO2@C18PMo12) showed the best photochromic performance, combining good coloration/decoloration kinetics with high color contrast (Delta E*(ab)= 25.8). Bi-component core-sheath-type fibers were prepared via melt spinning, using PP doped with 5 wt% of SiO2@C-18-PMo12 NPs as sheath and virgin PP as the core of the filaments. The resulting doped fibers presented good mechanical properties, which allowed the knitting of a photoresponsive mesh. The mesh showed UV-responsive properties, exhibiting similar optical features to those of the parent nanomaterial (coloration/decoloration kinetics and colorability). The results highlighted the remarkable thermal stability and robustness of the SiO2@C-18-PMo12 nanomaterial for up to T similar to 180 degrees C, without any decomposition or loss of photochromic performance, making it an attractive material for optical applications that require high processing temperatures.