Capsiate and phenolics present in the free, esterified, glycosylated, and insoluble-bound forms of BRS Moema peppers were characterized and quantified using UHPLC-ESI-MS/MS. Additionally, the in vitro antiproliferative activity of BRS Moema extract was evaluated. The peppers showed considerable quantities of capsiate and phenolic compounds. Esterified phenolics were the main fraction, followed by the insoluble-bound fraction, indicating that relying solely on the extraction of soluble phenolics may underestimate the total phenolic content. Among the fourteen phenolics identified in extract fractions, gallic acid was the major constituent. Phenolic fractions displayed high antioxidant capacity by TEAC and ORAC assays. Nevertheless, the correlation between phenolic compounds and antioxidant activity suggested that other bioactive or phenolic compounds may contribute to the overall phenolic compounds and antioxidant capacity of the obtained fractions. Concerning the antiproliferative activity, the extract did not exhibit any effect on cell proliferation within the evaluated concentration range. These findings indicated that BRS Moema peppers can serve as a rich source of phenolic compounds. Therefore, fully utilizing them could bring advantages to the food and pharmaceutical industries, as well as to consumers and producers.