Controlled and reversible ligand exchange reactions are useful tools for modulating reactivity of transition metal complexes. Here, we present a reversible electropolymerization of nickel azopyridine (azpy) complexes based on the redox-controlled diimine ligand exchange reaction. Upon a single electron reduction, (azpy)NiBr2 disproportionates to afford (azpy)2Ni and a [NiBr4]2−, while in situ 1e− oxidation of this mixture leads to complete restoration of the original complex. Reversible intermetallic ligand exchange is also demonstrated between nickel and cobalt or iron azopyridine complexes. This facile and quantitative ligand exchange reaction was utilized to develop a reversible electropolymerization strategy to generate nickel metallopolymers containing redox-active azobispyridine ligands.