In this study, a facile synthesis and grafting method is reported for tetradentate Cu(II) Schiff base complex onto the surface of graphene oxide (GO). The Schiff base Cu‐complex was synthesized through the condensation reaction between 2,3‐diamino pyridine and 2‐hydroxy‐1‐naphthaldehyde, followed by the addition of Cu(II) ion to afford N2O2‐Cu(II) complex. The GO was prepared through a modified Hummers’ method and characterized using various spectroscopic and microscopic techniques. The Schiff base Cu‐complex was then grafted onto the surface of GO via a simple solution‐phase reaction, resulting in the formation of N2O2‐Cu(II) Schiff base/GO composite. The fabricated composite was characterized using FTIR spectroscopy, UV–vis, X‐ray diffraction (XRD), and scanning electron microscopy (SEM). Importantly, the prepared N2O2‐Cu(II) Schiff base complex exhibited excellent DNA interaction as well as efficient antimicrobial and anticancer activities. Additionally, it demonstrated potent anticancer activity against hepatocellular carcinoma cells (HepG‐2), and colon cancer cells (HCT‐116) and exhibited promising activity against the COVID‐19 receptor (PDB ID: 6LU7) along with the human DNA receptor (PDB ID: 1BNA). Furthermore, this fabricated heterogeneous catalyst showed enhanced photodegradation of MB with ≈92% conversion and four times recyclability. The overall results suggest that the Cu(II) Schiff base/GO composite has potential applications in various medical and environmental fields, including photodegradation/elimination of harmful organic dyes for water treatment applications.