In triboelectric nanogenerators (TENGs), polymers are widely utilized, with plasticizers serving essential roles in industrial polymer applications. Plasticized polyvinyl chloride (PVC) dielectric gel TENGs are particularly effective at generating high outputs due to their strong triboelectric properties. However, elevated temperatures can cause plasticizer leakage due to weak interactions with the polymer matrix, reducing the TENG's stability. This study addresses these limitations by incorporating titanium dioxide nanoparticles (TiO2 NPs) into a dielectric gel, achieving significantly enhanced dielectric properties and thermal stability. The TiO2 NPs increase the dielectric constant, reduce leakage current, and improve output performance to 121 V, 11.1 μA, and 149 μW cm−2. Additionally, interactions between TiO2 NPs and polar components of the plasticizers prevent leakage, ensuring stability at high temperatures. The resulting nano-TiO2 dielectric gel TENG demonstrates superior mechanical and thermal resilience, enabling reliable operation in diverse environments. Furthermore, it features a temperature-independent pressure sensor with consistent sensitivity (S = 2.03 V kPa−1 for 10–40 kPa and S = 0.97 V kPa−1 for 40–100 kPa) and accuracy over a wide temperature range (25 °C to 55 °C). These properties make the nano-TiO2 dielectric gel TENG ideal for sustainable energy harvesting and temperature-robust sensing applications, enhancing the practical utility of TENGs across variable climates.