Titanium alloys are widely used in engineering applications for their high strength and corrosion resistance, but their poor tribological performance limits service life. Conventional surface treatments, such as micro-arc oxidation (MAO), improve hardness but suffer from surface porosity and limited wear resistance. Here, a composite coating combining MAO and chemical vapor deposition (CVD) diamond films was developed to enhance the tribological performance of titanium alloys. The CVD diamond layer effectively sealed MAO-induced pores and reduced surface roughness. Compared to the single MAO coating, the composite exhibited higher hardness under load, lower friction coefficient, and significantly reduced wear rate. Raman and SEM analyses confirmed improved surface integrity and reduced damage. Molecular dynamics simulations further revealed more uniform strain distribution in the MAO–diamond system, indicating enhanced structural stability. This dual-layer strategy offers a promising route for improving the wear resistance and durability of titanium alloys in demanding applications.