A multi-step synthetic strategy to polysulfone (PSU) grafted with phosphonated poly(pentafluorostyrene) (PFS) is developed. It involves controlled radical polymerization resulting in alkyne-end functional PFS. The next step is the modification of PSU with a number of azide side groups. The grafting of PFS onto PSU backbone is performed via the click-chemistry approach. In a final step, the PFS-grafts are subjected to the post phosphonation. The copolymers are evaluated as membranes for potential fuel cell applications through thermal analyses, water uptake, and conductivity measurements. The proposed synthetic route opens the possibility to tune copolymers hydrophilichydrophobic balance to obtain membranes with an optimal balance between proton conductivity and mechanical properties.