In the ongoing series of our research, we prepared a new multifunctional azo-vanillin ligand (HL) and its Cu(II) complex to investigate their potential as versatile compounds for industrial/pharmaceutical purposes. Structural integrity was determined through spectroscopic analyses (FT-IR, NMR, Mass and UV-Vis), highlighting a distorted square planar geometry for the metal complex. The ligand was examined for its dyeing potential on wool and cotton with the latter showing better substantivity to cellulosic fibers and behaving as a good direct dye having excellent washing fastness. Furthermore, leveraging its surface-active properties, the ligand was tested as a green corrosion inhibitor for C-45 steel in a saline medium (3.5% NaCl) across different temperatures. It achieved an outstanding inhibition efficiency of 92.82% at a 300 ppm concentration (298 K) via the formation of a protective adsorbed monolayer. On the biological side, cytotoxicity was tested against breast cancer cell lines MCF-7. The Cu(II) complex was found to be more active (IC50 = 93.8 μg/ml) than the free ligand, and the behavior of this complex could be rationalized in terms of Tweedy’s Chelation Theory along with increase in lipophilicity. These observations were supported by the theoretical density functional theory (DFT) method at the B3LYP/6-311++G(d,p) basis set for the ligand and the B3LYP/LanL2DZ basis set for the complex. To explain the molecular mechanism, in silico molecular docking was conducted against the VEGFR2 kinase domain. The ligand had a good binding affinity (-7.9 kcal/mol) primarily due to hydrophobic isosteric and electrostatic interactions. In addition, ADME profiling supported drug-like properties of the ligand and provided with a further acceptable pharmacokinetic behavior.