Watson, 19, who has just enrolled at Brown University in the US, acted as a creative advisor for the ethical fashion collection, which will reach shops in February.
"I wanted to help People Tree produce a younger range because I was excited by the idea of using fashion as a tool to help alleviate poverty and knew it was something I could help make a difference with," Sky News quoted her as saying.
"I think young people like me are becoming increasingly aware of the humanitarian and environmental issues surrounding fast fashion and want to make good choices but there aren't many options out there. It has been the most incredible gap year project," she added.
Among items that the teen actress has had a hand in designing were knitwear, cotton t-shirts, jersey dresses, and poplin shorts. Her range also includes some more bizarre items, including bohemian hand embroidered bed throws, recycled sweetie wrapper jewellery, banana fibre slouchy beanies and head scarves.
They will be sold by People Tree, a company which aims at supporting developing countries and promoting environmental projects.