Deep eutectic solvents (DESs), as novel, eco-friendly, cost-effective lubricants and additives, have increasingly been studied in recent years. However, their combination with commercial additives has seldom been reported. This study pioneers the design of a sulfur- and phosphorus-free oil-soluble DES combined with zinc dialkyldithiophosphate (ZDDP) additive in polyalphaolefin (PAO 40) base oil. The DES/ZDDP combination demonstrates superior compatibility and significantly enhances the physicochemical and tribological properties of PAO 40. At 588   N, lubrication failure occurs for both pure PAO 40 and PAO containing DES alone. In contrast, PAO with DES/ZDDP combination exhibits a 36% reduction in friction and a 43% reduction in wear compared to the PAO containing ZDDP alone. The chemical evolution of tribofilm across different friction stages reveals that DES firmly anchors at tribo-interfaces to form an initial protective film, synergizing with ZDDP for enhanced lubrication. Notably, DES accelerates the formation of ZDDP-generated tribofilm, effectively avoiding the running-in wear stage. During the steady-state friction stage, the chemisorbed DES layers and resultant tribofilm collectively hinder further tribochemical consumption of ZDDP, thereby preventing excessive wear of ZDDP and maintaining the stability of the ZDDP-formed tribofilm. Consequently, this synergistic effect between ZDDP and DES not only enables reduced ZDDP usage for greener lubricants but also opens up new avenues for the commercial application of DES as a lubricant additive.