Tobacco smoking is a major driver of premature mortality in people with serious mental illness (SMI; e.g., schizophrenia, bipolar disorder). This systematic literature review described randomized control trials of psychosocial smoking cessation interventions for people with SMI, rated their methodological rigor, evaluated the inclusion of racial/ethnic and sexual/gender minorities, and examined smoking cessation outcomes. Eligible studies included peer-reviewed articles published between 2009 and 2020 that examined psychosocial smoking cessation interventions in people with SMI. We used the Preferred Reporting Items for Systematic Review and Meta-analysis guidelines to conduct our review and the Methodological Quality Rating Scale to evaluate methodological rigor. Eighteen studies were included. Ten were categorized as high methodological rigor given their study characteristics (e.g., longer follow-up) and eight as lower methodological rigor based on their characteristics (e.g., not intent-to-treat). Racial/ethnic and sexual/gender minorities were under-represented in these studies. A range of psychosocial interventions were examined including motivational enhancements, smoking cessation education, cognitive behavioral strategies, and contingency management. Most studies also provided smoking cessation medications (e.g., NRT, bupropion), although provision was not always uniform across treatment conditions. Three studies found the intervention condition achieved significantly higher abstinence from smoking compared to the comparison group. Seven studies found the intervention condition achieved significantly higher reductions in smoking compared to the comparison group. Studies finding significant differences between the intervention and comparison groups shared common evidenced-based components, including providing smoking cessation medications (e.g., NRT, bupropion), motivational enhancement techniques, and cessation education and skills training, but differed in intensity (e.g., number and frequency of sessions), duration, and modality (e.g., group, individual, technology). Methodological limitations and a small number of studies finding significant between-group differences prevent the identification of the most effective psychosocial smoking cessation interventions. Clinical trial designs (e.g., SMART, factorial) that control for the provision of psychosocial medications and allow for the identification of optimal psychosocial treatments are needed. Future studies should also ensure greater inclusion of racial/ethnic and sexual/gender minorities and should be culturally/linguistically adapted to improve treatment engagement and study outcomes.