<p>Ostwald ripening (OR) and particle migration and coalescence (PMC)-induced sintering of metal nanoparticles remains a major challenge in heterogeneous catalysis. In the methoxycarbonylation of ethylene, noble metals such as Ru and Pd serve as active centers, yet inevitable metal aggregation during the reaction reduces both the number of active sites and catalyst lifetime. Herein, we report a highly efficient Ru catalyst supported on defect-rich TiO₂ with slight carbon coating for ethylene methoxycarbonylation. Systematic characterizations reveal that the thin carbon layer effectively suppresses OR, while appropriate metal–support interactions prevent PMC. The synergistic effect of these features maximizes the exposure of Ru⁰ active sites, enhancing catalytic activity and stability. The catalyst achieves a remarkable reaction rate of 13.18&#xa0;mol/mol_Ru/h and a selectivity of 99% toward methyl propionate, outperforming previously reported Ru-based catalysts. Furthermore, the catalyst retains over 90% of its activity after five consecutive cycles. This work provides a new strategy for designing robust and highly active catalysts for heterogeneous ethylene methoxycarbonylation.</p>