This article explores the relationship between children's knowledge and perceptions about their rights and subjective well-being (SWB) in a sample of 8-, 10- and 12-year-olds in 18 countries, taking account of gender differences. Children's knowledge and perceptions about their rights were analysed considering whether they reported that they knew their rights, whether they had heard about the UN Convention on the Rights of the Child (CRC) and whether they thought that, in their country, adults respected their rights. To explore SWB, a modified version of the Student's Life Satisfaction Scale, adapted by the Children's Worlds project, was used. Children reporting that they knew their rights, knew about the CRC, or thought that in their country adults respected their rights demonstrated significantly higher SWB scores than those reporting otherwise in the 18 countries. The effects of perceiving that adults in general respected children's rights in their own country on SWB were much more important than the knowledge of children's rights or the knowledge of the CRC. Results provide useful indications on how to promote children's well-being in public policies, including in education, through the promotion of their rights.