A new family of o-phenylenediamine substituted bis (aroyl selenourea) 1–3 were synthesised and characterised by spectroscopic methods and Single crystal XRD studies. The 1–3 showed that the synthesised compounds in crystallise in the monoclinic crystal system, and space group present is P 2/c, C 2/c and P 21/c. The computational studies of 1–3 were performed with Density function theory (DFT) using B3LYP/6-31G (d, p) level of theory. Molecular electrostatic potential map (MEP) and frontier molecular orbital (FMO) analysis were also carried out. Further molecular docking methods were used to recognise the binding of the molecules towards the molecular target DNA (PDB ID: 1BNA), BSA (PDB ID: 3V03) and human aromatase enzyme (PDB-ID: 3EQM). All compounds were screened for their cytotoxicity against breast cancer cell lines (MCF-7) and lung cancer cell lines (A549) under in vitro conditions. The compound 3 showed overall good cytotoxic activity and especially towards MCF-7 (IC 50 = 48.5 μM). AO/EB and Hoechst 33258 staining methods were used to analyse morphological changes to expose the mechanism of cell death. © 2018