Hexavalent chromium (Cr(VI)) is a highly toxic and carcinogenic pollutant that poses serious risks to human health and aquatic ecosystems. This study reports a novel green sol–gel approach for synthesizing mesoporous anatase TiO₂ nanostructures using chitosan and polyvinyl alcohol (PVA) as soft templating agents. The biopolymers enable homogeneous dispersion of the titanium precursor, forming a uniform gel network. Calcination at 400 °C completely removes the organic templates, producing pure anatase TiO₂ with a high BET surface area of 70 m²/g and narrow mesopores of 2–5 nm. The material exhibited excellent Cr(VI) removal performance, achieving a maximum adsorption capacity of 163.93 mg/g (Langmuir isotherm, R² = 0.9944) and following pseudo-second-order kinetics (R² = 0.9124), confirming chemisorption as the rate-controlling step. Under visible light, toxic Cr(VI) was effectively reduced to less harmful Cr(III), which was stably immobilized on the TiO₂ surface without significant pore blockage. This mechanism was verified by strong fluorescence in Raman spectra, enhanced hydroxyl and Cr–O bands in FTIR, a zeta potential shift from −57.2 mV to −48.1 mV, and Cr detection via EDX. The mesoporous structure remained stable after treatment (BET surface area ~72 m²/g). This low-cost, environmentally friendly biopolymer-templating strategy, optimized by Response Surface Methodology (RSM-CCD), provides a promising sustainable solution for heavy metal remediation in wastewater.