In this study, we synthesized the cobalt(II) chelation free complexes (1–3) with the general formula of [CoCl2L2] containing monodentate ligands (L=2‐methylbenzimidazole (L1), 2‐methylbenzoxazole (L2), and 2‐methylbenzothiazole (L3) and fully characterized by UV‐vis, FT‐IR spectroscopy, and the crystal structures of 1–3 were determined by X‐ray crystallography. Complexes 1–3 showed substantial antibacterial activity against tested bacteria. Complexes 2 and 3 were more active against S. aureus with the Minimum Inhibitory concentration (MIC) value of 12.5 μg/mL compared to other bacteria. Complexes 1–3 exhibited strong synergy with ampicillin (AMP) against Methicillin Resistant S. aureus strains (MRSA). Interestingly, complexes 2 and 3 in combination with AMP showed the membrane permeabilization of MRSA. This indicates that complexes 2 and 3 in combination with AMP had bacterial membrane disruption as a possible mechanism of action.