Abstract Background Depression is a mental disorder characterized by high and dysregulated negative affect in addition to diminished positive affect. To our knowledge, there has been no systematic review of the impact of psychotherapeutic interventions on these affective dimensions. Methods Two comprehensive literature searches for all randomized controlled trials of psychotherapy in adults with depression were performed. The first from 1996 to December 31, 2014 and the second from January 1, 2015 to December 31, 2015. The primary outcome was the mean score of positive and negative affect. Depressive symptoms were measured to be included as a predictor in the meta-regression analyses. Results Ten studies with 793 adults with depression were included. All studies assessed positive and negative affect. Psychotherapeutic interventions resulted in significantly increased positive affect ( g = 0.41; 95% CI: 0.16-0.66 p = 0.001), and significantly decreased negative affect g = 0.32; 95% CI: 0.15-0.78, p = 0.001) in depressed adults. Because of the small number and substantial heterogeneity of the existing studies the meta-regression analyses produced conflicting results. As a consequence, we were unable to sufficiently demonstrate whether NA and depressive symptoms are in fact correlated or not. Limitations Given the small number and heterogeneity of the included studies, the findings should be considered with caution. Conclusions Psychotherapeutic interventions demonstrate low to moderate effects in enhancing positive and reducing negative affect in depressed adults.