Metal and metal oxides nanoparticles (NPs) supported on polymer nanocomposites have recently received significant attention due to their valuable applications in catalysis. In this work, cellulose acetate butyrate/TiO2 (CAB/TiO2) and CAB/TiO2/Au nanocomposite films were fabricated via a nanosecond pulsed laser ablation method in liquid. The obtained nanocomposites were characterized by UV–Vis spectroscopy, Raman spectroscopy, Fourier transform infrared spectroscopy (FTIR), X-ray Diffraction (XRD), thermogravimetric analysis (TGA), and scanning electron microscopy (SEM). These techniques confirmed the formation of CAB/TiO2 and CAB/TiO2/Au nanocomposites. The catalytic performance of the fabricated nanocomposites was evaluated in the reduction of 2-nitrophenol (2-NP) to 2-aminophenol in the presence of sodium borohydride (NaBH4) as a reducing agent and quantitively was monitored by UV–Vis spectroscopy. The obtained results showed an excellent catalytic activity of the CAB/TiO2/Au nanocomposites, as 8 mg of the catalyst load resulted in ~ 100% conversion within a reaction time of 16 min. The reduction reaction of 2-NP follows the pseudo-first-order model, with rate constants of 0.0148, 0.0299, and 0.803 min−1 for 1 mg, 4 mg, and 8 mg catalysts loadings respectively. Moreover, the fabricated nanocomposites showed high stability and reusability, as it has been reused for the reduction of 2-NP up to 5 cycles without significant loss in catalytic activity.