Most colorectal cancers (CRC) arise from precursor lesions. We aimed to characterize the mutation profile of CRC precursor lesions in a Brazilian population. In total, 90 FFPE lesions, including 67 adenomas, 7 sessile serrated lesions, and 16 hyperplastic polyps, were analyzed by next-generation sequencing. The genetic ancestry of the patients was estimated. Somatic driver mutations were identified in 66.7% of cases, including alterations in APC (32.2%), TP53 (20.0%), KRAS (18.9%), BRAF (13.3%) and EGFR (7.8%). Adenomas displayed a higher number of mutations, mainly in APC, compared to serrated polyps (73.1% vs. 47.8%, p = 0.039). Advanced adenomas had a higher frequency of mutation in KRAS and GNAS and a high overall mutation rate than early adenomas (92.9% vs. 59%, p = 0.002). Concerning the serrated pathway, a higher frequency of mutations, mainly in BRAF, was observed in sessile serrated lesions (85.7%) compared to hyperplastic polyps (31.3%, p = 0.027). A high degree of ancestry admixture was observed in the population, with a predominance of European followed by African components. The mutation profile of Brazilian colorectal precursor lesions exhibits a similar landscape to other populations. These results bestow the knowledge of CRC's biological history and may contribute to a molecular screening approach.