Reversible addition–fragmentation chain-transfer (RAFT) polymerization of a methacrylate derivative bearing a difluorophosphonylated moiety, namely diisopropyl 1,1-difluoro-5-methacryloyloxy-pentylphosphonate, was successfully achieved for the first time in the presence of 4-cyano-4-(thiobenzoylthio)pentanoic acid as the chain transfer agent. Polymers with various molecular weights and low dispersities were obtained in a controlled way. Additionally, a new chain transfer agent containing a difluorophosphonated moiety (pCF₂-CTA) was successfully prepared to control the polymerization of methyl methacrylate and to create the pCF₂ functionality at the poly(methyl methacrylate) chain-end by RAFT polymerization. The dealkylation of phosphonate ester polymers was performed with excellent yields using bromotrimethylsilane.