Ronnie Fieg was born and raised in Queens, New York, the son of the owners of the famed Yellow Rat Bastard clothing store in SoHo. Fieg began working as a stock boy and salesman for footwear chain David Z, owned by his mother's first cousin at the age of 13. He eventually became the assistant manager, manager and buyer for David Z. 
Fieg's first collaboration was with Asics in 2007, where he designed 252 pairs of five different colors of the Gel Lyte III sneaker. Fieg would go on to maintain his relationship with Asics, and has consistently collaborated on many shoes since. 
Fieg has collaborated with other brands such as Adidas, Caminando, Chippewa, Clarks, Converse, Harris Tweed, Herschel Supply, New Balance, Polo Ralph Lauren, PUMA, Red Wings, Saucony, Sebago, Shades of Grey by Micah Cohen, Timberland and more. His total number of collaborations is guessed at over 50 products or more, making him one of the most prolific sneaker designers/collaborators of all time.
On November 11, 2011, Ronnie Fieg opened up his own apparel and footwear boutique called Kith NYC inside the Atrium clothing store. There are currently two locations, in Brooklyn and Manhattan respectively. Kith carries brands like Red Wing, Clarks, Asics, Danner, New Balance, Nike, Gourmet, and Native Footwear. The store often acts as a vessel for many of Fieg's limited edition sneaker collaborations, often being the exclusive retailer of the shoes.
- http://www.sneakerfreaker.com/articles/ronnie-fieg-new-yorks-gel-lyte-genius/. Missing or empty
- "RONNIE FIEG - NEW YORK'S GEL LYTE GENIUS". SneakerFreaker. Retrieved 22 November 2012.
- "Latest Products". RonnieFieg. Retrieved 22 November 2012.
- "About KITHNYC". KITHNYC. Retrieved 22 November 2012.