The daughter of a conductor father and a musical singer mother, she was born into and grew up in a musical family. She made her musical debut at twenty three with a joint concert with the Korean Symphony Orchestra. She then performed in numerous Korean musicals on national stage, for which she has recieved numerous awards. However, because of all its constraints she did not find that musical environment fulfilling.
She decided to go to Paris in 1995 to study jazz and French chanson at the CIM school - one of the oldest jazz schools in Europe - and at the National Music Institute of Beauvais, and at the Nadia and Lili Boulanger Conservatory. Her innate talent for jazz revealed itself when she started playing in Parisian jazz clubs with her group YSN 5Tet(which was formed in 1996).

She made her rounds around the Paris club scene. Performances that would earn her invitations to work together with many famous musicians. Youn Sun Nah made a strong showing in a number of jazz competitions like La Defense, St. Maur and Montmatre. She became the buzzword in theatres and festivals all over France, while also performing in Korea, essentially managing simultaneous careers in two countries.

Producing five albums in six years, she held numerous performances in France, Europe and in Asia, including Korea. Such vigorous activity would earn her the best artist prize in in crossover music category in Korea in 2003. In 2004, the release of So I Am was widely celebrated by French audiences as well as the press, who regarded her as one of the most remarkable singers of this generation. Active touring and active musical performances finally came to fruition in the form of the Grand Prize at the reputabel Jazz a Juan Concurs in 2005, in addition to a prize of the best young artist of the year in Korea.

She is an artist who never fails to move audiences wherever she may be performing, which led her to over 100 successful performances in Europe, USA, Australia, and Asia in 2005 and 2006. Youn Sun nNah reestablished her position as a premier jazz artist in in the Asian music scene and marketplace with the album Memory Lane co-produced with Denmark's top pianist Niels Lan Doky and and Korean bassist Kim Jeong-ryul. She also earned regonition from the American media and noted personalities from around the world with an invitation and performance at the Jazz at Lincoln Center, which would launch her to world stardom. Meanwhile, she has worked with world-famous Swedish artists like Ulf Wakenius and Lars Danielsson on her newest album Voyage. The new album will hit the market in Korea in September 2008 and to the rest of the world in April 2009 through ACT, one of the top jazz labels in the world.