We developed a novel platform that was constructed using an in-situ technique to simultaneously synthesize sub-nano Zn-Co on the metal–organic framework (MOF) with a dodecahedron size of 150 nm. The hybridization structure of sub-nano Zn-Co MOF has been demonstrated through shifts of diffraction peaks (XRD patterns) and shake-up satellite peaks, shifting negativity of metallic Co (XPS spectra). The electrochemical dopamine (DA) sensing mechanism was thoroughly analyzed. The sub-nano Zn-Co MOF hybrid material has shown excellent electrochemical results in detecting DA detection at extremely low concentrations. Results from DPV showed that the Zn-Co MOF/GCE has a linear range of 0.01–300 µM of DA and a limit of detection of 6.72 nM. The interference experiments of neurotransmitters (UA, GABA, AA, Gly, Ser) demonstrated not much effect on amperometry changes of DA. Especially, sub-nano Zn-Co MOF/GCE electrode indicated good results in the serum samples, high reproducibility, and can practical application. With advantages including a simple, environmentally friendly, non-enzymatic production process, high selectivity, and reproducible outcomes, DA-detecting sub-nano Zn-Co MOF that has been developed can be used for the initial diagnosis of neurological disorders, the functional evaluation of dopaminergic neurons, chemicals or drugs on human neuronal cells.