<p>The development of high-performance thermal interface materials (TIMs) is crucial for addressing the escalating thermal management challenges in modern electronics. While incorporating high-thermal-conductivity fillers is a common strategy, enhancing the intrinsic thermal properties of the polymer matrix remains a significant challenge. This study presents a novel approach by synthesizing cerium-ion-bridged polydimethylsiloxane (PDMS) fluids (VC and HC, terminated with dimethylvinylsiloxy and dimethylsiloxy groups, respectively) via an anionically catalyzed non-equilibrium polymerization of cyclic siloxane (D3) using CeCl₃ as a bridging agent. These fluids were comprehensively characterized by GPC, FT-IR, and NMR techniques, confirming the successful incorporation of Ce and the tailored polymer structures. Subsequently, a series of thermally conductive silicone gels was prepared by employing VC-1 as the matrix and the HC series as crosslinkers, with 70 vol% hydrid-sized spherical Al₂O₃ as the filler. The results demonstrate that the cerium ion concentration plays a pivotal role in determining the thermal performance. The gel with the highest Ce³⁺ concentration (2.61&#xa0;ppm) achieved a superior thermal conductivity of 2.62 W/(m·K), representing a 13.62% enhancement compared to a cerium-free control. In a practical simulation test using a 100 W high-brightness LED, the optimal gel (Sample A, containing 2.37&#xa0;ppm Ce) reduced the chip's surface temperature by 16.1&#xa0;°C (a 7.84% reduction) compared to a commercial thermal gel, despite the latter having a higher nominal thermal conductivity. This performance is attributed to the improved interfacial compatibility and reduced phonon scattering within the cross-linked network, facilitated by the presence of cerium ions. This work provides new insights into the molecular-level design of polymer matrices for advanced thermal management materials.</p>