Increasing discharges of industrial wastewater, along with ever-stricter regulations for the protection of natural water sources, have amplified the demand for highly efficient water treatment technologies. Here, electrospun nanofibrous polyimides enhanced with ion exchange properties are proposed as adsorptive membranes for the treatment of dye-loaded textile wastewater. With the careful selection of monomers, carboxyl-functionalized porous polyimides are synthesized in a single step and then further decorated with strong cation and anion exchange side groups. Nuclear magnetic resonance spectroscopy and thermal gravimetric analysis are used to investigate the alkylation degree and total exchange capacity of the polymers. The electrospinning conditions are optimized to produce highly flexible membrane mats with a uniform nanofibrous structure. A series of dye sorption experiments on the nanofibrous membranes reveals the adsorption kinetics and the effects of the polyimide backbone, the charged side groups, and the hydrophilicity. A recycling study is conducted to confirm the stability of the adsorbent membranes. The results suggest that nanofibrous polyimide membranes enhanced with ion exchange properties are promising candidates for the treatment of dye-laden wastewater. Owing to their facile syntheses and unique properties, these membranes show promising potential in environmental applications.