A facile route to well-defined boronic acid (co)polymers from stable and easily manipulated boronic ester monomers is presented. The polymerization of 4-pinacolatoborylstyrene by reversible addition-fragmentation chain transfer (RAFT) yielded polymeric boronic acid precursors. Selection of stoichiometry allowed tuning of polymerization kinetics and targeting specific molecular weights in the range of M-n = 17000-32000 g/mol. The resulting low polydispersity poly(4-pinacolatoborylstyrene) homopolymers were employed as macro-chain transfer agents for block copolymerization with N,N-dimethylacrylamide to yield amphiphilic block copolymers that formed micelles in aqueous media. The pinacol ester derivatized (co)polymers were easily deprotected by a mild and convenient strategy to yield free boronic acid polymers.