Born on New York’s Upper East Side, Minnie spent her childhood between Manhattan, Palm Beach and Southampton.  After graduating from boarding school, Minnie moved to Paris to pursue her love of all things design. She took a position with Italian photographer Oberto Gili, and travelled the world assisting him on his shoots. It was on her travels that she met her future husband, Academy Award winning film-maker Stephen Gaghan. He taught her to surf, they fell in love and moved to Malibu where Minnie designed her very first dress.  Vogue Magazine took notice, and featured Minnie and the dress in their Spring 2009 issue. The overwhelming response spurred Minnie to try her hand at designing a line. That fall she released her first complete collection.

   To date Minnie's designs have been sold in hundreds of boutiques in the US as well as boutiques in Japan, Italy, Brazil, Germany and England. She has been featured in the pages of Vogue, Elle, Marie Claire, Vogue Nippon, The Wall Street Journal, Vanity Fair, Harpers Bazaar, InStyle, WWD, Lucky, Cosmopolitan,  Style.com and many others. 

   Minnie and her designs have appeared on both Good Morning America and Good Day LA. She also played herself on the CW's cult show "Gossip Girl."

   In 2010 she partnered with the W Hotels to design an exclusive collection for the hotel’s boutiques worldwide.  

   Spring 2013 will mark the release of her second co-branded women’s line for life style brand Boast USA, for whom she is both a designer and creative consultant. In August 2012, Minnie along with Project and W Magazine, co-hosted a celebration of Boast’s 40th anniversary at the Cosmopolitan Hotel in Las Vegas. She styled and walked in the event’s main attraction: a poolside fashion show.  

   Most recently, Minnie has partnered with fellow California brand Three Dots for a ten-piece capsule dress collection, marking the first co-branded collaboration for Three Dots in it's 17 years of existence. Three Dots co-founder and CEO Sharon Lebon told ELLE.com, the partnership was “ideal,” since “Minnie’s cool and classic sense of style resonates so well with our woman.” The ten-piece women’s line includes a  maxi dress, a bandage dress and a cargo jacket. The Minnie Mortimer signature stripes are featured, along with prints and solids. The collection is manufactured in Three Dot's Orange County factory and sold under the label "Minnie Mortimer for Three Dots"