In this study, bimetallic nanoparticles (NPs) of Co–Pt anchored on cellulose nanofibers (CNFs) for catalytic applications were synthesized via a sonochemical approach. The electro-spinning technique was employed for the synthesis of CNFs from cellulose acetate. The thorough characterization of synthesised Co–Pt/CNF nanocomposites was performed with the help of scanning electron microscopy (SEM), Fourier transform infra-red (FT-IR) spectroscopy, field emission scanning electron microscopy (FESEM) with energy dispersive X-ray analysis (EDX), and X-ray diffraction (XRD). This method leads to the facile preparation of Co–Pt bimetallic NPs using cellulose as a support. The synthesized nanocomposites were used for the p-nitrophenol (p-NP) reduction to p-aminophenol (p-AP) with excess sodium borohydride (NaBH₄) to assess their catalytic performance. The effects of various parameters on the performance of the catalyst were also investigated. The investigated parameters are catalyst loading, initial p-NP concentration and NaBH₄ concentration. The extent of p-NP reduction into p-AP over Co–Pt/CNF nanocomposites with an excess of NaBH₄ was examined with UV-vis spectroscopy. The p-NP reduction to p-AP over Co–Pt NPs anchored on CNFs was achieved within 98 seconds with around 100% conversion. The efficiency of the catalyst did not vary significantly up to 5 consecutive cycles. The excellent catalytic activity (K_app = 0.028 s⁻¹) and stability of the as-synthesized Co–Pt nanoparticles supported on CNFs make them potential catalysts for nitrophenol reduction and wastewater treatment.