Polyolefins with antimicrobial properties are generally prepared through blending or coating with antimicrobial agents. However, the nonpolar nature of polyolefins brings many issues including the difficulties in homogeneous mixing. In this contribution, we report the synthesis of polyolefins with intrinsic antimicrobial properties through three different routes. First, direct copolymerization of ethylene with nitrogen-containing comonomers affords some nitrogen-functionalized polyolefins with moderate antimicrobial properties. Subsequently, two postpolymerization functionalization routes enable the formation of imidazolium and various metal ion-functionalized polyolefins through the conversion of preinstalled chlorine and carboxylic-functional groups. In addition to high molecular weight and high functional group incorporation, these alternative routes generate polyolefins with excellent mechanical and antimicrobial properties. This work demonstrates the importance of different functional groups in determining the antimicrobial properties of polyolefin materials.