Uranium extraction from seawater employing chemical adsorbents is considered to be a promising strategy to conquer the scarcity of uranium resources. Regrettably, shortcomings of poor adsorption performance and saturated adsorption hinder the development of adsorption strategies to extract uranium from natural seawater where the environment is complicated. Herein, a sulfonated perylene-based conjugated microporous polymer adsorbent (PyB-SO₃H) is prepared. The excellent photocatalytic activity of PyB-SO₃H ensures the effective generation of active oxygen species (˙O₂⁻ and ¹O₂), which have high antibacterial activity. Moreover, it also promotes photoelectrons to reduce the adsorbed hexavalent uranium to insoluble tetravalent uranium, and facilitate electrostatic attraction of the photogenerated holes to the negative [UO₂(CO₃)₃]⁴⁻, thus greatly enhancing the uranium extraction capacity. Owing to this photo-enhanced synergistic effect, the uranium extraction capacity of PyB-SO₃H in 500 ppm uranium(VI)-spiked seawater reaches 1.989 g g⁻¹, with a nearly 90% extraction efficiency. This research provides a unique perspective for the development of high-efficiency adsorbents for uranium extraction from seawater.