Concerned significant others (CSOs) of people who experience gambling problems may also experience harm. This systematic review provides an updated summary of research published between 2011 and 2021 on interventions for CSOs. A total of 17 reports were found to be relevant and were included in the review. Many studies involved online interventions, such as Cognitive Behavioural Therapy (CBT). Most interventions were directed at treating the CSOs alone. The authors of this review used the stress-strain-coping-support model (SSCS) as a starting point for categorizing treatment process descriptions.