The present disclosure provides an affinity polypeptide for the purification of a recombinant biologically active protein or polypeptide. Further, the present disclosure provides a fusion recombinant protein or polypeptide wherein the fusion recombinant protein comprises of at least two components, a biologically active polypeptide or protein or protein of interest and the affinity polypeptide. The biologically active polypeptide may be linked directly or indirectly to the affinity polypeptide by covalent binding. The present disclosure provides a recombinant expression vector for the producing said fusion recombinant protein in host cells. Further, the present disclosure provides an improved method of purification of recombinant protein from the host cells. Further, the disclosure provides a method of purification of the recombinant biologically active polypeptide or protein by immobilized metal ion chelating chromatography.