This work presents the successful synthesis of an Au/carbonized botanical leaf functionalized-electroactive polyimide nanocomposite as a catalyst for the reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP). The organic functional groups from the carbonized botanical leaves not only wrapped in EPI via π-π interaction to form carbonized botanical leaf functionalized-electroactive polyimide (CX-EPI and CN-EPI) but also increase the surface area of the nanocomposite and provide active sites as reducing agent and carrier for Au nanoparticles (AuNPs) to obtain the final product, Au/CX-EPI and Au/CN-EPI nanocomposites. The successful incorporation of organic functional groups and AuNPs was characterized by FT-IR, BET, XRD, SEM, and HR-TEM. The in-situ reduction reaction that mediated between the electroactive segment, polyphenolics, and HAuCl4 solution were confirmed by XPS spectroscopy. Furthermore, the Au/CX-EPI and Au/CN-EPI nanocomposites show excellent catalytic activity and recyclability for the reduction of 4-NP to 4-AP. The reaction rate constants for Au/CX-EPI and Au/CN-EPI were calculated as 2.0 × 10−3 and 3.1 × 10−3 s−1, respectively. Moreover, both catalysts exhibited a conversion of higher than 95% after ten cycles of catalytic reduction reactions. These nanocomposites from carbonized plants and electroactive polyimide as promising potential heterogeneous catalysts for various catalytic reactions.