The cashew nut is an important product in Brazil, both for consumption and export, with the pulp of the cashew fruit being considered a by-product despite its high flavonoid content. In this study, the use of cashew pulp extract as a treatment for acne and in the prevention of early skin damage was investigated. Its flavonoid content was determined using spectrophotometric identification, and its effects on cell and bacterial viability, the migration of keratinocytes, and antioxidant activity in vitro were evaluated. Furthermore, it was incorporated into an emulsion for topical administration, and the physical-chemical stability parameters of the formulation were determined. The cashew pulp contained flavonoids with healing and antioxidant activity, and was not toxic to keratinocyte cells in a viability test. The flavonoid-rich formulation was stable, indicating that this is a promising formulation for use in the treatment of acne and protection of skin against premature damage.