The reactive co‐polymer approach is one of the most promising techniques for the synthesis of functional polyolefins. Following this concept, 1‐hexene and p‐methylstyrene are co‐polymerized in the presence of a generic Brookhart‐type catalyst. The microstructures of the co‐polymers imply the tendency of p‐methylstyrene co‐monomers to place at the end of the structural branches formed by the chain walking reaction. The molar masses of the co‐polymers decrease, not only at higher levels of co‐monomer but surprisingly by decreasing reaction temperature. A mechanism consisting of a highly stable η3 metal–benzyl intermediate, which is quantitatively approved by density functional theory calculations, can delicately justify all the aforementioned observations. A series of the produced co‐polymers is selectively functionalized by maleic anhydride at the benzylic position of p‐methylstyrene, under very mild reaction conditions. Such a reactive intermediate opens the path for the introduction of different types of functionalities in polyolefins. Namely, the grafted co‐polymers were further functionalized by a triazole ring, which provides a transient supramolecular network through intermolecular hydrogen bonding.