Lignin serves as a primary abundant source of renewable aromatic compounds. Achieving efficient breakdown of lignin and retaining its aromatic properties is highly desirable but remains a challenging task. To address this challenge, we synthesized Anderson-type polyoxometalate (POM) catalysts, particularly [CTAC]2[CoMo6]. We then investigated the effectiveness of the POM catalysts in the oxidative depolymerization of larch lignin. Under conditions of 160 °C, 1.0 MPa oxygen atmosphere, and a catalyst-to-substrate ratio of 1:5, we achieved a monomer yield of phenolic compounds at 12.43 wt%. The unsaturated coordination sites of Mo5+ within the catalysts were identified as active sites, facilitating enhanced O2 adsorption and activation. The enhanced O2 adsorption significantly influenced the production of aromatic monomers from lignin. We observed that the catalysts effectively cleaved CC bonds in β-O-4 dimer compounds using lignin dimer model compounds. Notably, the [CTAC]2[CoMo6] catalyst exhibited excellent stability across five cycles, maintaining its high efficiency in lignin depolymerization. This indicates that Anderson-type POM-based catalysts exhibit potential for sustainable conversion of biomass into valuable compounds and for enhancing lignin valorization processes.