Epoxy-TiO2 nanocomposites' thermal stability was thoroughly examined throughout a wide range of nanoparticle loadings, ranging 0.5 wt% to 20 wt%. An optimized ultrasonic dual-mixing technique ensured uniform distribution of titania nanoparticles within the viscous epoxy system. The study investigated how the glass transition temperature (Tg) and thermal stability of the nanocomposites are affected by inter-particle spacing and nanoparticle cluster size. Atomic force microscopy was used to characterize nanoparticle dispersion in epoxy. Tg was estimated using differential thermal analysis, and thermogravimetric analysis was employed to examine the thermal stability of the nanocomposites. It was found that a nanoparticle content around 10 wt% serves as a critical threshold for noticeable improvements in Tg and thermal stability. These enhancements are attributed to the formation of a robust epoxy-nanoparticle interface, driven by the even distribution of nanoparticles, it prevents the epoxy polymer chains from moving freely. Moreover, the nanoparticles' ceramic characteristics limit heat transfer through the matrix by acting as thermal insulators.