This work presents a cost-effective TiO₂ nanocomposite doped with Sn+2 (1.8wt%) and activated carbon (1 wt%) used as an active layer in hydrogen gas sensing applications. The prepared nanocomposite has a particle size of 46 ± 2 nm, roughness 4.31 nm, high surface area (202 ±11 m²/g), and a bandgap of 2.7 eV. It was synthesized via a simple sol-gel method followed by calcination at 500 °C, to enhance room-temperature H₂ gas sensing. A thin film (470 ±10 nm thick) was deposited on silicon via chemical bath deposition, exhibiting an anatase-rutile structure, 150 ± 10 nm grains, 3.2 eV bandgap, and roughness (45 nm RMS) as confirmed by XRD, FTIR, AFM, SEM, and UV-Vis analyses. The sensor demonstrated superior performance to H₂ (100–5000 ppm), achieving 45.7% sensitivity at 1000 ppm, response/recovery times of 18/42 s, showing competitive performance compared to selected Sn-doped TiO₂ and carbon-based sensors due to synergistic oxygen vacancies, porosity, and p-n junction effects—enabling reliable detection for safety-critical applications.