Purpose: Cancer patients' intimate partners often experience levels of psychological burden that are comparable to or even exceed that of the patients, making it imperative that they too be provided with appropriate psychological support. This review aimed to present the content and the effects of interventions delivered to caregiving partners of cancer patients on both partners and patients. Furthermore, we provide information about the acceptability of the interventions and study quality. Methods: An initial search in Web of Science, PsycINFO, and PubMed databases was conducted. We included RCTs as well as pre-post studies that focused on enhancing partners' wellbeing or diminishing partners' distress. To be included, interventions had to have been offered to partners either only or predominantly. We included studies published until December 2017. The methodological quality of the trials was assessed with the EPHPP assessment tool. Results: Nine studies met the inclusion criteria. Intervention topics included social support, short-term problem solving, the marital relationship quality, role expectations, emotional resilience, and coping strategies. Positive intervention effects were found with regard to social support, emotional distress, improved communication, posttraumatic growth, self-efficacy, and coping. Despite considerably low response rates, the interventions were generally well accepted. Most of the studies suffer limitations because of methodological flaws, the lack of randomization, and small sample sizes. Conclusion: Interventions delivered to partners of cancer patients may have positive effects on both partners and patients. We derive several implications for future research: Intervention programs should be tailored to the specific needs of caregiving partners with regard to the cancer trajectory and gender. Effort has to be made to increase sample sizes as well as to include particularly burdened individuals. Selected measurement instruments should be sensitive to specific intervention effects. Finally, information on both statistical as well as clinical relevance of research findings should be provided.