Purpose Social support is important for maintaining and restoring psychological well-being but the effects of individual psychotherapies on perceived social support are not well known. In this analysis of secondary outcomes from a randomized clinical study, we compared the effects of long-term psychotherapy and two short-term psychotherapies on social support during a 5-year follow-up. Materials and methods Altogether 326 adult outpatients suffering from depressive and/or anxiety disorders were randomly assigned to long-term psychodynamic psychotherapy (LPP, n = 126), short-term psychodynamic psychotherapy (SPP, n = 101) and solution-focused therapy (SFT, n = 97). Outcome was measured by the global index and six subscores of the self-reported Brief Inventory of Social Support and Integration scale (BISSI) at baseline and at 1, 2, 3, 4 and 5 years after the beginning of the therapy. Results Social support improved in all therapy groups and the improvement was relatively stable, lasting several years after the end of therapy. Little difference in improvement was observed either between therapy orientations or durations. Conclusions While no major differences were observed between treatment groups, the slight differences call for further research to verify these findings and to better understand how different therapies may improve perceived social support.