This systematic review and meta-analysis aimed to investigate whether cognition is associated with activity and participation outcomes in adult stroke survivors. Five databases were systematically searched for studies investigating the relationship between general- and domain-specific cognition and longer-term (>3 months) basic activities of daily living (ADL), instrumental ADLs, and participation outcomes. Eligibility for inclusion, data extraction, and study quality was evaluated by 2 reviewers using a standardized protocol. Effect sizes ( r ) were estimated using a random-effects model. Sixty-two publications were retained for review, comprising 7817 stroke survivors (median age 63.57 years, range:18–96 years). Median length of follow-up was 12 months (range: 3 months–11 years). Cognition (all domains combined) demonstrated a significant medium association with all 3 functional outcomes combined, r =0.37 (95% CI, 0.33–0.41), P <0.001. Moderator analyses revealed these effects persisted regardless of study quality, order in which outcomes were collected (sequential versus concurrent), age, sample size, or follow-up period. Small to medium associations were also identified between each individual cognitive domain and the separate ADL, instrumental ADL, and participation outcomes. In conclusion, poststroke cognitive impairment is associated with early and enduring activity limitations and participation restrictions, and the association is robust to study design factors, such as sample size, participant age, follow-up period, or study quality. Cognitive assessment early poststroke is recommended to facilitate early detection of disability, prediction of functional outcomes, and to inform tailored rehabilitation therapies.