The non-polar nature of polyolefins, alongside providing the valuable properties that mark them as one of the most important modern polymers, also entails that their application in standard processes such as blending, adhesion and dyeing remain highly problematic. Recently, advances in C–H functionalization chemistry have allowed the development of numerous post-modification techniques which enable the direct introduction of functional groups thereby enhancing the function and value of these materials. The objective of this Perspective article is to highlight the present state of polyolefin post-modification research, especially concerning recently developed C–H functionalization chemistry. The article additionally contains discussion regarding challenges remaining within the field, and also suggests strategies for its advancement. The article is divided into sections organized by the atom that substitutes the C–H bond of the polyolefin, and includes sections on halogenation and dehydrogenation.