Models strutted in a line through a tiered catwalk of five square compartments, pausing in each to showcase midriff-bearing mesh tops and yellow shift dresses.
Denim tank tops were teamed with slouchy jeans, while thigh-high slits featured heavily in the figure-hugging dresses and monochrome skirts.
Rihanna followed the conventions of catwalk shows, appearing momentarily at the end of the display to take bow from the centre of the stage.
The boyish, casual designs are Rihanna's first with River Island, a clothing chain which traces its history on Britain's high streets back 64 years and is known for its youthful clientele.
"I loved it - it's so Rihanna, it's got Rihanna's name all over it," said model Tolula Adeyemi from Los Angeles, who was in the crowd. "I kind of want the whole collection, it's got plenty of swag."
The fashion credentials of the high street have grown in recent years, as more household clothing brands inch onto the catwalks of major fashion centers.
The Barbados-born singer has already made a foray into fashion, teaming up with Armani Jeans in 2011.
(Editing by Alison Williams)