This article presents the synthesis of a novel mononuclear Co (II) complex [Co(9‐BuA)2Cl2] (1), its characterization, supramolecular packing pattern, theoretical calculations, anticancer properties, and molecular docking studies. Complex 1 was generated from 9‐butyl adenine (9‐BuA) building block and characterized by spectroscopic methods (FT‐IR, mass, elemental analysis) and single crystal X‐ray diffraction analysis. The cobalt (II) ion in complex 1 is distorted in its tetrahedral environment. The Co+2 is coordinated to the two rare N1 binding sites of the pyrimidinate moiety of two 9‐BuA ligands and two chlorine atoms occupying the axial positions. Both intramolecular and intermolecular hydrogen bonds support the formation of supramolecular assembly and stabilize the crystal structure. The nature of the intermolecular interactions in the supramolecular network was also decoded by Hirshfeld surface analysis and molecular surface contours (dnorm). The percentage contributions are represented by 2D fingerprint plots. The average energy between dimers was determined by the energy framework analysis, and the crystal packing's three‐dimensional topology was also investigated. Density functional theory (DFT) has been used to ascertain the geometry and interactions in the complex. The cytotoxic effects of Co (II) complex 1 and corresponding 9‐BuA ligand were investigated in Dalton's lymphoma (DL) malignant cancer cells and on normal peripheral blood mononuclear cells (PBMCs) to evaluate their anticancer activity. Finally, molecular docking analyses have been carried out to analyze the nature of molecular interactions between Co (II) complex 1 and the receptor.