Breast cancer is a heterogeneous pathology, but the genomic basis of its variability remains poorly understood in populations other than Caucasians. Here, through DNA and RNA portraits we explored the molecular features of breast cancers in a set of Hispanic-Mexican (HM) women and compared them to public multi-ancestry datasets. HM patients present an earlier onset of the disease, particularly in aggressive clinical subtypes, compared to non-Hispanic women. The age-related COSMIC signature 1 was more frequent in HM women than in those from other ancestries. We found the AKT1E17K hotspot mutation in 8% of the HM women and identify the AKT1/PIK3CA axis as a potentially druggable target. Also, HM luminal breast tumors present an enhanced immunogenic phenotype compared to Asiatic and Caucasian tumors. This study is an initial effort to include patients from Hispanic populations in the research of breast cancer etiology and biology to further understand breast cancer disparities.