Admission to a smoke-free setting presents a unique opportunity to encourage smokers to quit. However, risk of relapse post-discharge is high, and little is known about effective strategies to support smoking cessation following discharge. We aimed to identify interventions that maintain abstinence following a smoke-free stay and determine their effectiveness, as well as the probable effectiveness of behaviour change techniques (BCTs) used in these interventions. Systematic review and meta-analyses of studies of adult smokers aged ≥18years who were temporarily or fully abstinent from smoking to comply with institutional smoke-free policies. Institutions included prison, inpatient mental health, substance misuse or acute hospital settings. A Mantel-Haenszel random-effects meta-analysis of randomized controlled trials (RCTs) was conducted using biochemically verified abstinence (7-day point prevalence or continuous abstinence). BCTs were defined as 'promising' in terms of probable effectiveness (if BCT was present in two or more long-term effective interventions) and feasibility (if BCT was also delivered in ≥25% of all interventions). Thirty-seven studies (intervention n=9041, control n=6195) were included: 23 RCTs (intervention n=6593, control n=5801); three non-randomized trials (intervention n=845, control n=394) and 11 cohort studies (n=1603). Meta-analysis of biochemically verified abstinence at longest follow-up (4weeks-18months) found an overall effect in favour of intervention [risk ratio (RR)=1.27, 95% confidence interval (CI)=1.08-1.49, I2 =42%]. Nine BCTs (including 'pharmacological support', 'goal-setting (behaviour)' and 'social support') were characterized as 'promising' in terms of probable effectiveness and feasibility. A systematic review and meta-analyses indicate that behavioural and pharmacological support is effective in maintaining smoking abstinence following a stay in a smoke-free institution. Several behaviour change techniques may help to maintain smoking abstinence up to 18months post-discharge.