The phytogenic synthesis method to highly active, recoverable and recyclable heterogeneous copper oxide nanocatalyst and encapsulated within biomaterial that acts as a nontoxic and renewable source of reducing and stabilizing agent. The biosynthesized CuO NPs were characterized using UV–Vis absorption spectroscopy, X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), energy dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM) and thermo gravimetric analysis-differential scanning calorimetry (TGA–DSC), techniques. The formation of CuO NPs with the size 20–45 nm range is shown in TEM image. Significantly, in aqueous phase CuO NPs have high catalytic activity for the reduction of Congo red (CR), methylene blue (MB) and 4-nitrophenol (4-NP) in the presence of the sodium borohydride (NaBH4) at room temperature. In addition, CuO NPs catalyst can be easily recovered by centrifugation and reused for 6 cycles with more than 90% conversion efficiency. CuO nanocatalyst, leaching after catalytic application was investigated by ICPAES (Inductively coupled plasma atomic emission spectroscopy). CuO NPs possess great prospects in reduction of pernicious dyes and nitro organic pollutants in water.