The star sued Topshop's parent company Arcadia for 3.3m pounds over the T-shirts, which featured a photo taken during a video shoot in 2011, reported BBC online.
Her lawyers told the High Court in London the fashion chain duped fans and may have damaged her reputation. They said the picture was "very similar" to images used on CD sleeves for one of her albums.
Judge, Justice Birss, ruled that a "substantial number" of buyers were likely to have been deceived into buying the T-shirt because of a "false belief" that it had been approved by the singer. He said it was damaging to her "goodwill" and represented a loss of control over her reputation in the "fashion sphere".
Topshop's lawyers had claimed the 25-year-old was making an unjustifiable bid to establish a "free standing image right" over use of her picture in the UK. The photograph used by Topshop had been taken during filming of a music video in Northern Ireland in 2011.
In a two-minute judgement Birss, said there was "no such thing as a general right by a famous person to control the reproduction of their image". "The taking of the photograph is not suggested to have breached Rihanna's privacy.
The mere sale by a trader of a T-shirt bearing an image of a famous person is not an act of passing off. "However, I find that Topshop's sale of this T-shirt was an act of passing off," he continued.