A biosynthesis of Copper Nanoparticles supported on Zeolite Y and its application as efficient, reusable, heterogeneous catalyst in C−N cross coupling reactions between amines and aryl halides are reported. The biosynthesis of CuNPs/Zeolite Y was achieved by the reduction of CuSO4.5H2O with the lemon juice (without peal) and encapsulated into the Zeolite Y in a single step. In this biosynthetic method, the ascorbic acid present in the lemon juice acted as a reducing agent for CuSO4.5H2O. The CuNPs/Zeolite Y was characterized using UV‐Vis, powder XRD, FT‐IR, HR SEM, EDS and TGA. The average size of the CuNPs are found to be 50 nm and has large surface area for the efficient catalysis. The new catalyst is effect in catalyzing the C−N cross coupling reaction between amines and aryl halides (yield ranging from 89% to 95% depends on amine and aryl halide used). The catalyst can be recovered from the reaction mixture by simple procedure. The recovered catalyst is found to be active in catalyzing the coupling reaction even after five runs.