It's now been confirmed Parisian designer will come up with a line for the shop, to be available this autumn.
The Swedish retailer is famed for its collaborations with big name stars, with Donatella Versace and Karl Lagerfeld previously designing for the store.
The collection will go on sale in 250 stores worldwide on November 14 and will boast clothing and accessories. The line will also mark the first time Isabel will design menswear.
"I am flattered by this collaboration: H&M works with the best designers and this invitation is an exciting honour," Isabel said in a statement. "I aim at creating something real, that women want to wear in their everyday lives, with a certain carelessness, which I think is very Parisian: you dress up, but do not pay too much attention and still look sexy. The collection is infused with this kind of easiness and attitude. Everything can be mixed following one’s own instincts: my take on fashion is all about personality."
Isabel is known for her urban and rocky aesthetic, which H&M bosses are hoping she will bring to the collection. The line is expected to be a sell out when it launches.
"We are excited to have Isabel Marant as a guest designer at H&M," the company's Creative Advisor Margareta van den Bosch said. "The way she mixes different elements in her collections, creating a style that is effortless and urban, makes her very contemporary. She has a fantastic eye for ethnic detail and the rare ability to create something that people really want to wear. We are sure the H&M customers will be enthusiastic about this collection."