Newly emerging two-dimensional (2D) materials of MXenes possess lots of merits, which provide potential solutions for the lubrication issues in harsh conditions. Here, preliminary efforts were devoted to developing an MXene-based 2D composite coating and its antiwear interfacial performance in ambient environments. Macroscale and atomic-scale characterizations were utilized to explore the lubrication behaviors of the composite coating to clarify the influence of the coating composition and tribo-test parameters in the establishment of ultra-wear-resistant sliding interfaces. The results highlighted a unique lubrication mechanism for the 2D MXene composite coating. They suggested that the MXene/nanodiamond coating exhibited almost no wear when rubbed against a polytetrafluoroethylene (PTFE) ball. A nanostructured tribofilm with unprecedented bonding features was in situ formed along the sliding interface. The ultra-wear resistance highly depended on the combined effects of shielding and self-lubrication of PTFE, layer shearing of MXenes, and self-rolling of nanodiamond. These discoveries clearly enrich the 2D material-based lubrication theories and offer technical guidance for designing and exploiting high-performance ultra-wear-resistant materials.