To conduct critical assessment of the literature on the effects of cochlear implantation on adults' cognitive abilities.PubMed, Scopus, Lilacs, Web of Science, Livivo, Cochrane, Embase, PsycInfo, and grey literature were searched. Eligibility criteria: age 18 or over with severe-to-profound bilateral hearing loss, cochlear implantation, cognitive test before and after implantation. Risk of bias was assessed using ROB, ROBINS-I and MASTARI tools. Meta-analysis was performed.Out of 1830 studies, 16 met the inclusion criteria.On AlaCog test, significant improvement was found after implantation [MD = -46.64; CI95% = -69.96 to -23.33;Cognitive improvements after cochlear implantation may depend on time and the cognitive task evaluated. Well-designed studies with longer follow-up are necessary to examine whether cochlear implantation has a positive influence on cognitive abilities. Development of cognitive assessment tools to hearing-impaired individuals is needed.