We report herein cobalt-catalyzed enantioselective and chemodivergent reactions between a cyclopropanol and an oxabicyclic alkene via a cobalt homoenolate, which afford either an alkylative ring- opening product or a hydroalkylation product, with the counterion of the cobalt catalyst being a major chemoselectivity-controlling factor. A catalyst generated from cobalt(II) chloride and a chiral diphosphine promotes alkylative ring opening to afford 1,2-dihydronaphthalen-1-ol derivatives in good yields with high enantioselectivity. By contrast, a catalyst generated from cobalt(II) acetate and the same diphosphine ligand, with the assistance of methanol, selectively affords hydro- alkylation products with retention of the bicyclic structure at a comparable level of enantioselectivity.