Online interventions that elicit kindness may enhance well-being. We tested the efficacy of three kindness interventions among breast cancer survivors. Participants (N = 137, M age  = 62.65 years) were randomized to perform acts of kindness for others, acts of kindness for self, self-kindness meditation, or a daily-activities-writing control and completed three activities each week for 4 weeks. Primary (well-being, depressive symptoms) and secondary outcomes (social support, self-kindness) were assessed pre- and post-intervention. No differences emerged in the primary outcomes. However, relative to controls, participants in the acts of kindness to others condition reported greater increases in social support, and participants in the self-kindness meditation condition reported greater decreases in self-kindness. Among breast cancer survivors, performing prosocial acts may enhance feelings of social support. The two self-kindness conditions yielded either null or detrimental effects, suggesting that further research is needed on best practices for conducting self-focused kindness interventions.