We prove here that Mo supported on Ti-modified dendritic mesoporous silica nanoparticles (DMSN) is an excellent catalyst for the oxidative desulfurization of model compounds and real crude oils. The catalyst was synthesized; characterized; tested in the removal of benzothiophene, dibenzothiophene, and 4,6-dimethyl dibenzothiophene; and re-tested in the sulfur removal from Arabian extra light crude oil under the optimized conditions. The can remove 92.5–99.5% of the most refractory compounds in the optimized conditions of 80 °C. For the Arabian Extra light crude oil (AXL), we employed Fourier-transform ion cyclotron resonance (FT-ICR) to analyze in detail the sulfur-containing compounds in the feedstock, oxidized product, and extraction phase. The sulfoxide species with low double bond equivalent (DBE) can be removed entirely after the stage 1 extraction.