We describe a comprehensive genomic characterization of 91 adrenocortical carcinoma specimens. Analysis identified several new ACC driver genes including PRKAR1A, RPL22, TERF2, CCNE1, and NF1. Genome-wide analysis revealed frequent occurrence of massive DNA loss followed by whole-genome doubling (WGD), associated with aggressive disease. WGD was identified as a hallmark of ACC progression, supported by increased TERT expression, decreased telomere length, and cell-cycle activation. Integrated molecular subtyping identified three ACC subtypes with distinct clinical outcomes and alterations, which could be captured by a 68-CpG DNA-methylation signature for clinical stratification.