Summary Poor solubility of π-conjugated two-dimensional polymers (C2Ps) has been a significant roadblock in incorporating these emergent materials into electronic devices by simple solution processing. Here, we report a rational design of triphenylene-based building blocks that condense via a series of reversible reactions for self-error-correction and a final irreversible fixation to form a pyrazine motif, which leads to the formation of crystalline C2Ps in solution without any aid of template or preorganization. Unlike typical covalent organic frameworks, remarkably, these materials remain dispersed as single- to few-layer films in solution, presumably because of protonation of pyrazine motifs by the strong acid employed in the synthesis. The C2Ps can be easily drop-cast onto solid surfaces for characterization and fabrication of electronic devices. The thin polymer films display a long-range internal order and exhibit high hole mobility up to 4 cm2V−1s−1, the highest among C2Ps, which paves the way to design high-performance optoelectronic devices.