Leveraging the high reactivity, modularity, and orthogonality of the SuFEx reaction, we report here the SuFEx iterative exponential growth (SuFEx IEG) method for synthesizing uniform polymers and block copolymers (BCPs) with molecular weights up to 21 kDa. The key step in SuFEx IEG was the orthogonal activation of the pair of functional groups, the SuFEx-inactive tetrahydropyranyl and imidazylate groups, into SuFEx-active tert-butyldimethylsilyl and sulfonyl fluoride. The modular nature of the SuFEx click reaction enabled the synthesis of uniform polysulfates, including hydrophilic polysulfates, that served as modules to create BCPs and triblock copolymers without molecular weight distribution. The chain ends of the polymers and BCPs were used to prepare uniform cyclic polymers and BCPs via intramolecular SuFEx cyclization. The SuFEx IEG method provides a robust and versatile approach for precisely constructing uniform polymers, as well as sequence-defined polymers.