The 25-year-old R&B star's team tried to negotiate with Topshop owners for eight months over the rights to the image, reported Ace showbiz.
"Rihanna's team asked Topshop a number of times to stop selling her image. However, the fashion giant owned by billionaire Sir Philip Green told the singer that it would continue selling the T-shirts.
"(Topshop's owners) buy the pictures from a photographer, but they do not pay the artist licensing fees. Unfortunately, UK law does not protect the artist," a source said.
"Even though the UK laws don't protect the artist, she has decided to move forward and sue Topshop. She has spent almost USD 1 million in litigation at this point. She says it's the principle, and wants to make a statement about it. They are taking advantage of artists. It is just exploitation. What they are doing is wrong," the source added.
Rihanna has reportedly hired international lawyer Reed Smith to file the suit in London.