Background. The aim of this study was to assess the efficacy of meaning-centered group psychotherapy for cancer survivors (MCGP-CS) to improve personal meaning, compared with supportive group psychotherapy (SGP) and care as usual (CAU). Method. A total of 170 cancer survivors were randomly assigned to one of the three study arms: MCGP-CS (n = 57); SGP (n = 56); CAU (n = 57). The primary outcome measure was the Personal Meaning Profile (PMP; total score). Secondary outcome measures were subscales of the PMP, psychological well-being (Scales of Psychological Well-being; SPWB), post-traumatic growth (Posttraumatic Growth Inventory), Mental Adjustment to Cancer (MAC), optimism (Life Orientation Test-Revised), hopelessness (Beck's Hopelessness Scale), psychological distress (anxiety and depression, Hospital Anxiety and Depression Scale; HADS) and quality of life (European Organization for Research and Treatment of Cancer Quality of Life Questionnaire; EORTC QLQ-C30). Outcome measures were assessed before randomization, post-intervention, and after 3 and 6 months of follow-up (FU). Results. Linear mixed model analyses (intention-to-treat) showed significant differences between MCGP-CS, SGP and CAU on the total PMP score, and on (sub)scales of the PMP, SPWB, MAC and HADS. Post-hoc analyses showed significantly stronger treatment effects of MCGP-CS compared with CAU on personal meaning (d = 0.81), goal-orientedness (d = 1.07), positive relations (d = 0.59), purpose in life (d = 0.69); fighting spirit (d = 0.61) (post-intervention) and helpless/hopeless (d = -0.87) (3 months FU); and distress (d = -0.6) and depression (d = -0.38) (6 months FU). Significantly stronger effects of MCGP-CS compared with SGP were found on personal growth (d = 0.57) (3 months FU) and environmental mastery (d = 0.66) (6 months FU). Conclusions. MCGP-CS is an effective intervention for cancer survivors to improve personal meaning, psychological well-being and mental adjustment to cancer in the short term, and to reduce psychological distress in the long run.