The construction of vicinal stereocentres—particularly sterically bulky quaternary motifs—from racemic alkyl halides remains a formidable challenge. Here, a cobalt-catalysed enantioconvergent reductive addition of racemic alkyl halides to imines has been developed, enabling efficient synthesis of diverse contiguous stereocentres, including tertiary–tertiary, tertiary–quaternary and quaternary–quaternary stereocentres, with high diastereo- and enantioselectivities.