After radical resection, patients with adrenocortical carcinoma (ACC) frequently experience recurrence and, therefore, effective adjuvant treatment is urgently needed. The aim of the study was to investigate the role of adjuvant platinum-based therapy. In this retrospective multicentre cohort study, we identified patients treated with adjuvant platinum-based chemotherapy after radical resection and compared them with patients without adjuvant chemotherapy. Recurrence-free and overall survival (RFS/OS) were investigated in a matched group analysis and by applying a propensity score matching using the full control cohort (n = 268). For both approaches, we accounted for immortal time bias. Of the 31 patients in the platinum cohort (R0 n = 25, RX n = 4, R1 n = 2; ENSAT Stage II n = 11, III n = 16, IV n = 4, median Ki67 30%, mitotane n = 28), 14 experienced recurrence compared to 29 of 31 matched controls (median RFS after the landmark at 3 months 17.3 vs. 7.3 months; adjusted HR 0.19 (95% CI 0.09-0.42; P < 0.001). Using propensity score matching, the HR for RFS was 0.45 (0.29-0.89, P = 0.021) and for OS 0.25 (0.09-0.69; P = 0.007). Our study provides the first evidence that adjuvant platinum-based chemotherapy may be associated with prolonged recurrence-free and overall survival in patients with ACC and a very high risk for recurrence.