Porous polyacrylonitrile (P-PAN) nanofibers containing a conjugated microporous polymer (CMP) with photocatalytic ability were electrospun to obtain a reusable photocatalyst composite. P-PAN nanofiber was used as a robust supporting matrix for the CMP and could prevent undesirable CMP leakage during use. To provide porous nanofibers, poly (vinyl pyrrolidone) was used as a sacrificial porogen, allowing facile access of dye molecules to degrade, or of the organic reagent to react. When exposed to visible light, the photocatalyst composite degraded rhodamine B (RhB) by more than 90% in 150 min. In addition, more than 85% of the RhB degradation was maintained even after 10 cycles of reuse. The nanofibrous photocatalyst was able to oxidize various benzylamine derivatives to convert to N-benzylbenzaldimines under visible light. It could also be reused several times for repeated photocatalytic organic reaction after simple washing.