The present study aims to understand the importance of corporate social responsibility (CSR) as a factor influencing the purchase intention of Portuguese Millennials in the cosmetics sector, using the Theory of Planned Behavior. The study was developed based on a quantitative methodology, applied using an online questionnaire, answered by 193 Millennials. The results demonstrate that attitude, control, and concern are predictors of the intention to purchase socially responsible cosmetics and that CSR is an influencing factor of the purchase intention of Portuguese Millennials surveyed in the cosmetic industry sector. These results have implications for business performance, in a context where we are witnessing the emergence of a more aware and informed consumer market, in which the Millennial Generation fits, and where the criteria of CSR are considered in consumption. It also has implications for scientific research on the subject in Portugal where studies are still relatively scarce.