<p>Advanced thermal interface materials (TIMs) require high contents of ceramic fillers to exhibit both high isotropic thermal conductivity and suitable rheological viscosity for ensuring low contact thermal resistance. Traditional approaches for achieving this balance often fail and pose ongoing academic and industrial challenges. We develop a novel approach for enhancing both the rheological mobility and thermal conductivity of magnesia (MgO)/polydimethylsiloxane (PDMS) TIMs by employing Ce- and Ti-assisted liquid-phase sintering of MgO fillers (CT-MgO fillers) using a scalable spray-drying method. The liquid-phase sintering of MgO fillers with Ce and Ti additives, which facilitate low-temperature sintering and densification, results in higher thermal conductivity of TIM (8.2 W m⁻¹&#xa0;K⁻¹ at a filler content of 80 vol.%) compared with commercial alumina filler-based TIMs. Additionally, the hydrophobic surface of CT-MgO fillers enables efficient mixing with PDMS and allows high-loading TIMs (80 vol.%) to maintain a thixotropic state, thereby effectively reducing contact thermal resistance with a copper substrate. This filler-modification strategy, which also provides electrical insulation, is expected to promote the development of high-performance polymer-based TIMs for advanced electronics.&#xa0;</p> Graphical Abstract <p>Liquid-phase sintering with Ce and Ti additives in heat-dissipating fillers provides excellent thermal conductivity and suitable rheological viscosity to achieve low contact thermal resistance of filler/PDMS composites. This strategy is expected to promote the development of high-performance oxide-based TIMs for use in advanced electronic applications.</p> <p></p>