Background: High rates of re-offending indicate that young custody-leavers face challenges when reintegrating into their communities. Aftercare/resettlement programs can occur pre-, during, and post-release and generally provide multiple forms of support services to address youths’ transitional needs. Objectives: To examine the impact of youth aftercare/resettlement programs on criminogenic outcomes, and how treatment effect is moderated by participant, program, and study characteristics. Methods: Keywords and synonyms were combined in a Boolean search across 26 electronic databases. Grey literature sources included 23 journals, 4 meeting archives, 11 organization websites, and 3 open access journal websites. The search was completed in January 2023. Included studies used a randomized controlled design or quasi-experimental comparison group design in which participants were matched on at least some baseline variables, and used at least one quantitative individual-measure of crime. Only studies conducted in a westernized country, and published after 1991 in English, French, or German were considered. Data analysis: Study risk of bias was addressed using the ROBINS-I and the ROB-2. Quantitative outcomes from evaluations of aftercare interventions were synthesized using random effects models and meta-regression. Results: The search resulted in 15 impact studies, representing 4,718 participants across 21 program sites, and 35 effect sizes. No significant effects were found for arrest (k = 14; OR = 1.044, 95% prediction interval [0.527, 2.075], t = 0.335) or incarceration (k = 8, OR = 0.806, 95% prediction interval [2.203, 1.433], t = -1.674). A significant pooled effect was found for conviction (k = 13, OR = 1.209, 95% prediction interval [1.000,1.462], t = 2.256), but results were highly sensitive to the inclusion of specific studies. No meaningful pattern of results emerged in moderator analyses with respect to study, sample, program component, or program delivery characteristics. Conclusions: Current evidence is promising with respect to conviction outcomes but overall does not find that aftercare/resettlement interventions have a reliably positive impact on criminogenic outcomes for young offenders. High variability across outcomes and reported data resulted in small sample sizes per outcome and limited moderator analyses. Additional rigorous research is sorely needed to further investigate the nuances of the program effects.