MXene, as an emerging two-dimensional (2D) material with ultrathin structure and fascinating physiochemical properties, has been widely explored in broad applications. Versatile functions of MXenes are continuously explored. This work presents distinctive feature of MXene-Ti₃C₂T_x nanosheets for free-radical (FRs) scavenging that never reported before. We demonstrated the mechanism and equation in regard to the reaction between Ti₃C₂T_x and H₂O₂, which was applied to design colorimetric H₂O₂ strip assay with good performance. The good FRs scavenging capability of Ti₃C₂T_x, including a series of reactive oxygen species (ROS) and reactive nitrogen species (RNS), was systemically confirmed. The antioxidation capability of Ti₃C₂T_x for protecting cells from oxidative damage was demonstrated using the oxidative damage model of alpha mouse liver 12 (AML-12) cells. This original work provides huge opportunities for MXenes in FR-related biomedical applications.