The invention relates to a novel use of a mimosa seed extract for the preparation of a cosmetic and/or dermatological composition for topical application, intended to combat the signs of skin ageing. The mimosa seed extract can be advantageously combined with an extract of marigold. The invention also relates to a cosmetic process for combating the signs of skin ageing, which consists in applying to the skin a composition containing an effective amount of mimosa seed extract.