Bis Schiff base N,N–((1E,2E)‐ethane 1,2diylidene)bis(azanylylidene)di(isonicotinohydrazide) ligand L was reacted with Fe (III), Ni (II), Co (II), and Hg (II) chlorides to yield complexes (1–6). The structure of the synthesized ligand and metal complexes was well established by various spectroscopic techniques (Fourier‐transform infrared [FT‐IR], UV–Vis., and 1H NMR), mass spectrometry, elemental analysis (CHN) and physical studies (thermogravimetric analysis [TGA]/first derivative thermogravimetric analysis [DTG], powder X‐ray diffraction, molar conductance, and magnetic moment). Solid powder samples of the binuclear complexes (3 and 6) were irradiated at two different irradiation doses (150 and 200 kGy) to yield complexes (3F and 3F*) and (6F and 6F*), respectively. For the γ‐irradiated samples, FT‐IR, UV–Vis., and physical studies (TGA/DTG, X‐ray diffraction, molar conductance, and magnetic moment) were performed using the same methods as for the as‐prepared complexes. In addition, calf thymus ct‐DNA binding results monitored by agarose gel electrophoretic method indicated that the as‐prepared binuclear [Hg2LCl4(OH)2] complex (6) and its γ‐irradiated [Hg2LCl4(OH)2] complex (6F) have the ability to cleave ct‐DNA at a concentration of 30 and 70 μg/ml, respectively. Inhibitory activity against hepatocellular carcinoma cells (HepG‐2) and breast carcinoma cells (MCF‐7) of ligand and as‐prepared complexes (3, 6, and 6F) was evaluated. The results revealed that metal complexes exhibited enhanced activity in comparison to the free ligand, and the as‐prepared complex (6) shows an IC50 value of 5.7 ± 0.2 and 8.72 ± 0.6 μg/ml for the two cell lines, respectively. Docking process for the ligand and complexes (3) and (6) with liver cancer protein (ID: 4FM9) and breast cancer protein (ID: 1H7K) has been evaluated.