Hydrophilic-hydrophobic blocky copolymers of poly(ether ether ketone) (PEEK) were prepared using a two-step post-polymerization technique. First, PEEK was brominated in the semicrystalline gel state to create a blocky BrPEEK template, which was subsequently functionalized by sulfonating the remaining runs of unfunctionalized PEEK units. The resultant degree of sulfonation of the blocky brominated, sulfonated PEEK (BrSPEEK) copolymers was inversely related to the degree of bromination, and degrees of sulfonation ranging from 26 to 71 mol% were obtained for degrees of bromination between 27 and 144 mol%. Thermal analysis using DSC and DMA revealed distinct multi-phase behavior for blocky BrSPEEK copolymers at degrees of sulfonation up to 40 mol%, suggesting phase separation between the densely brominated blocks and the sulfonated blocks into hydrophobic and hydrophilic domains, respectively. This phase separation contributed to improved dimensional stability upon swelling and enhanced proton transport at lower water content for blocky BrSPEEK membranes compared to random SPEEK membranes. Finally, morphological analysis using SAXS demonstrated that ionic aggregate size remained relatively unchanged for blocky BrSPEEK at all degrees of sulfonation, and the ionic aggregates became more closely spaced with increasing degree of sulfonation. Overall, this work demonstrates a facile, post polymerization technique to prepare hydrophilic, hydrophobic blocky copolymers with excellent dimensional swelling and transport properties that rival those of directly polymerized block copolymers.