Nitrogen‑grafting through the addition of glycine (Gly) was performed on a metal‑ phenolic network (MPN) of copper (Cu2+) and gallic acid (GA) to increase its adsorption capacity. Herein, we reported a one‑step synthesis method of MPN, which was developed according to the metal–ligand complexation principle. The nitrogen grafted CuGA (Ng‑CuGA) MPN was obtained by reacting Cu2+, GA, and Gly in an aqueous solution at a molar ratio of 1:1:1 and a pH of 8. Several physicochemical measurements, such as Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), N2 sorption, X‑ray diffraction (XRD), and thermal gravimetry analysis (TGA), were done on Ng‑CuGA to elucidate its characteristics. The analysis revealed that the Ng‑CuGA has non‑uniform spherical shaped morphology with a pore volume of 0.56 cc/g, a pore size of 23.25 nm, and thermal stability up to 205 °C. The applicational potential of the Ng‑CuGA was determined based on its adsorption capacity against methylene blue (MB). The Ng‑CuGA was able to adsorb 190.81 mg MB per g adsorbent at a pH of 6 and temperature of 30 °C, which is 1.53 times higher than the non‑grafted CuGA. Detailed assessment of N g‑CuGA adsorption properties revealed their pH‑ and temperature‑dependent nature. The adsorption capacity and affinity were found to decrease at a higher temperature, demonstrating the exothermic adsorption behavior.