OBJECTIVE: To update the evidence on the effects of financial incentives (FI) on physical activity (PA) in adults. METHODS: A systematic search of nine databases (Medline, EMBASE, PsychINFO, Scopus, Web of Science, CINAHL, EconLit, SPORTDiscus, and Cochrane) was conducted to identify randomised controlled trials (RCTs) and pilot RCTs published between June 1, 2018 and March 31, 2024 examining FI-for-PA interventions. 'Vote counting' and random-effects meta-analyses assessed short- (<
6 months) and long-term (≥6 months) FI effects, as well as impact during follow-up (incentive withdrawal). Meta-regressions examined moderator effects. RESULTS: Twenty-nine studies (n = 21 RCT, n = 8 pilot RCTs
median FI size = .19 USD/day) involving 9604 participants were included (60.8 % female, mean age = 42.7 years). 17 of 21 studies reported positive short-term effects. 5 of 5 and 3 of 8 studies, respectively, reported positive long-term and follow-up effects. Among the 15 studies included in daily step count meta-analyses (most commonly reported PA outcome), FI had a moderate effect during short-term interventions (standardized mean difference [SMD] [95 % CI] = 0.52 [0.25-0.78], p <
0.001) and a small effect in follow-up (SMD [95 % CI] = 0.20 [0.01-0.40], p = 0.04). Too few long-term studies reported daily step count to conduct pooled analyses (n = 1). Meta-regressions suggest study length, incentive size, wearable device-use, and goal setting moderate FI effects (p <
0.05). CONCLUSIONS: Twenty-nine studies were identified over a 6-year span. Short-term FI interventions increase PA. The impact on daily step count is clinically significant (≥1000 steps/day). Key contextual factors moderate effects. Evidence is limited regarding long-term and follow-up effects.