Corrole is known as a contracted tetrapyrrolic macrocycle bearing an α,α'-linked bipyrrole moiety. Using a unique trianionic N4 donor environment at the inner core, various high-valent metal species have been examined for potential catalytic applications. To seek new reactivity of metallocorroles, we have previously designed and synthesized a specific carbacorrole ligand, namely N-confused/N-linked corrole analogs.[1] The former analog contains an inverted pyrrole moiety connected at the α and β’-linking positions, and the latter has a peculiar linkage between the pyrrole α-position and the pyrrolic nitrogen site. The distinct [NNNC] coordination environment of these carbacorroles stabilizes unique organometallic species such as a copper(III).[2]In this work, we synthesized novel cobalt complexes with a benzo-fused corrole analog (i.e., benzonorrole). The electronic structure of the resulting complex is highly dependent on the number of axial pyridine ligands. The bis-pyridine adduct complex can be regarded as a diamagnetic Co(III) species. Removal of an axial pyridine ring from the corresponding complex yielded the oxygenated product at the inner carbon site immediately. Unlike the bis-pyridine adduct, the mono-pyridine cobalt complex is a singlet Co(II) ligand radical at the ground state as inferred from various spectroscopic means and DFT calculations. Due to the intrinsic redox-noninnnocent character, the cobalt(II) radical complex exhibits facile reduction nature. On this basis, we finally applied for catalytic hydrogen evolution reaction with these cobalt complexes.[1] Fujino, K.; Hirata, Y.; Kawabe, Y.; Morimoto, T.; Srinivasan, A.; Toganoh, M.; Miseki, Y.; Kudo, A.; Furuta, H. Angew. Chem. Int. Ed. 2011, 50, 6855-6859; Toganoh, M.; Kawabe, Y.; Uno, H.; Furuta, H. Angew. Chem. Int. Ed. 2012, 51, 8753-8756.[2] Maurya, Y.; Noda, K.; Yamasumi, K.; Mori, S.; Uchiyama, T.; Kamitani, K.; Hirai, T.; Ninomiya, K.; Nishibori, M.; Hori, Y.; Shiota, Y.; Yoshizawa, K.; Ishida, M.; Furuta, H. J. Am. Chem. Soc. 2018, 140, 6883-6892.