Polyethylene (PE) is the most heavily used polymer worldwide. Considerable efforts have focused on modifying properties of PE via cross-linking. In contrast to previous cross-linking methods, which generate PE thermosets of low process-ability, here, we report the development of a dynamic covalent networking additive (DCNA) that possesses the PE backbone and reconfigurable network with alkyl boronic esters as novel dynamic linkages. The addition of DCNA at 5 wt % provides PE materials with clearly improved mechanical (e.g., tensile strength, Young's modulus, and yield strength) and rheological (e.g., creep resistance) properties at elevated temperatures. Moreover, the obtained materials could be easily reprocessed, recycled, and 3D-printed, creating opportunities toward sustainable and high-performance PE materials.