Copper complexes are renowned for their efficiency in the treatment of cancer because of their cytotoxic effect on tumour cells. Using a variety of techniques, including ESI-Mass, NMR, FT-IR, UV–Vis, TG-DTA plots, CV, ESR, Molar conductance, DFT, and Hirshfeld surface analysis, Pyrazolone based HLB ligand and [Cu(HLB)(DMF)] complex were synthesised and characterized. The synthesized copper complex is square pyramidal in nature in which four oxygens of ligand coordinated to central copper metal at an axial position and one oxygen from DMF solvent bind at an equatorial position which can be proved by single crystal analysis. UV–Visible spectroscopy to identify charge transfer and D-d transition in the complex. To evaluate and obtain an excellent correlation with all experimental findings, DFT calculations have been done using the B3LYP/6–31 G basis set. The HOMO-LUMO energy gap, NBO charges, and MESP are useful to confirm the characteristics theoretically and to know the physical and chemical properties of such system. Hirshfeld surface analysis has been done to know the hydrogen bonding and secondary interaction in molecule. Electrochemical analysis such as cyclic voltammograms (CV) provides an idea about the redox behaviour of synthesized copper complexes. To prove the paramagnetic behaviour of a complex ESR/EPR was done at room temperature in a solid state. Using Lung adenocarcinoma (NCI-H23), Hepatocellular carcinoma (HepG2), and Neuroblastoma (SH-SY5Y) cell lines the anticancer activity of a synthesized complex was examined. Scratch assay, Calcein and EthD-1 staining were also used. Moreover, the Inhibition of cell migration using synthesized compound has been evaluated by scratch assay. Apoptotic cell death has been observed by differential staining.