The fashion line started in 1994, when Castiglioni became known for her contributions to the design of fur, stemming from her husband's family fur business. At the time, fur was typically designed in an old-fashioned manner, but Castiglioni instead treated it as a normal fabric to make modern, wearable clothing. Her fashion line, named after her sister Marni, grew as her customers needed something to wear under or with their fur.
Today, the company produces ready-to-wear clothing, handbags, jewelry, and eyewear. Jenna Lyons, senior vice president of women's design for J.Crew, attributes Marni's success to the "post-Tom Ford era," saying that women are lately being bold through color, print, and shape rather than through overt sex appeal and are dressing more for other women than for men. Marni launched its first menswear line in Fall 2007, introducing leggings as standalone bottoms for men.
In November 2011, H&M announced a collaboration plan with Marni, to be launched in spring 2012. In 2013, the brand launched its first fragrance, Marni.
By the end of 2012 the majority in Marni was acquired by Renzo Rosso, President of OTB Group, the holding group of Maison Martin Margiela, Viktor & Rolf, Diesel and Staff International.
Castiglioni, who has always been the label's chief designer, is responsible for Marni's aesthetic of "European-inflected bohemianism." Other descriptors that have been applied to Marni designs include "quirky," "feminine," "off-beat," and "funky." Early design features included idiosyncratic prints and vintage-inspired shapes and fabrics; Marni has retained these elements but has become more streamlined. Other Marni hallmarks include juxtapositions of texture; colorblocking; a palette focused on gray, beige, and blue, in which bright colors are interspersed; and unusual shapes, such as bell hemlines, gathering, asymmetry, and large volumes.
The interior of theLondon Marni store
Marni sells clothing in sixteen countries; boutiques locations include London, New York City, Los Angeles, Las Vegas, Beijing, Shanghai, Sydney, Moscow, Kuwait, Hong Kong and Tokyo. Online sales began in 2006. Marni's line is made in Italy, and does not have any licensees.
Castiglioni's husband, Gianni, is Marni's CEO, and their daughter Carolina runs the online store. The company's annual sales in 2007 were approximately $100 million: Though the company has been approached by potential investors and buyers, so far Castiglioni is uninterested in selling as of 2007.