Born Kara Jankelowitz, in Johannesburg to an Ashkenazi Jewish family, Janx moved to New York City after obtaining a degree in architecture. She then became a fashion designer and launched her first collection in 2002. In 2009 Janx won the title of International Sportswear Designer of the Year, and then in 2011 she launched a successful bridal-wear line. On 14 January 2007, Janx married Sharone Sohayegh (sometimes referred to as Red) in South Africa. Sharone is involved in real estate. Kara gave birth to her first child, a 6 lb. 14 oz daughter named Dylan on 12 November 2007. She gave birth to her second child, a boy named Noam, in 2009.
On Project Runway, Janx lasted eleven episodes before being eliminated. She was, however, in the bottom two in the eighth episode, the Inspiration challenge, and in the bottom three during the seventh episode, the On Thin Ice challenge. She was one of the last four contestants remaining and just missed a spot in the final three at New York City's Olympus Fashion Week. Janx did get to show her collection at Fashion Week as a decoy so that viewers would not know who was actually in the final three until her last episode aired later that week. On Project Runway All-Stars, Janx made it all the way to the seventh episode before being eliminated.