The title ligand, [1‐(2‐methoxyphenyl)‐3‐(4‐chlorophenyl)]triazene, HL (1), was prepared. In a reaction with Hg(NO3)2 it forms the complex [Hg(C26H22Cl2N6O2)], [HgL2] (2). Both compounds were characterized by means of X‐ray crystallography, CHN analysis, FT‐IR, 1H NMR, and 13C NMR spectroscopy. In the structure of compound 1, two independent fragments are present in the unit cell. They exhibit trans arrangement about the –N=N– double bond. The dihedral angles between two benzene rings in both fragments are 4.36 and 18.79 Å, respectively. Non‐classic C–H···N hydrogen bonding and C–H···π interactions form a layer structure along the crystallographic ab plane [110]. In compound 2, the HgII atom is hexacoordinated by two tridentate [1‐(2‐methoxyphenyl)‐3‐(4‐chlorophenyl)]triazenide ligands through a N2O2 set. In addition, in the structure of 2, monomeric complexes are connected to each other by C–H···π stacking interactions, resulting in a 2D architecture. These C–H···π edge‐to‐face interactions are present with H···π distances of 3.156 and 3.027 Å. The results of studies of the stoichiometry and formation of complex 2 in methanol solution were found to support its solid state stoichiometry.