A new sequential post-polymerization modification process was developed, which comprised a sulfonamidation reaction between poly(pentafluorophenyl 4-vinylbenzenesulfonate) (poly(PFP-4VS)) and amines and a subsequent Mitsunobu reaction on NH moieties of the obtained polymeric sulfonamides. We have successfully demonstrated the utilization of this new sequential post-polymerization modification by synthesizing a library of functional polymers.