The brand confirmed rumours of the collection on its official Style Insider blog today (July 16).
Rihanna said: "I've been wanting to design my own collection for some time. River Island is the perfect partner for me to collaborate with and working with a British, family-run business also really appealed to me.
"I find London really inspiring and River Island loves to have fun with clothes. I'm looking forward to working with them and creating something really special."
River Island added: "We're so pleased to announce an exciting collaboration with Rihanna. Yep, she will be designing her first clothing range exclusively for River Island.
"We're all huge fans of Rihanna's style here at River Island so you can imagine how flattered we were when she approached us about working together and bringing our fashion experience to her range."
The collection will launch in Spring 2013.