Born and raised in Queens, New York, Fieg began working for footwear chain owner David Z at the early age of 15. He started out at one of the David Z stores as a stockboy doing long hours, while going to Cardozo High School and slowly worked his way up to salesmen. From here he proceeded up the ladder to assistant manager, manager and finally buyer. Working for David Z gave Fieg the unique ability to be at the epicentre of the world of fashion; Manhattan. He would also go on to accumulate a large shoe collection, becoming one of the largest collections on the East Coast.
Fieg's earliest collaboration was with Asics in 2007, where he designed five different colorways for their Gel Lyte III series shoe. The shoes would go on to sell all 252 pairs available in one day and even grace the cover of the Wall Street Journal. Fieg would go on to maintain his relationship with Asics, so much so that he has collaborated with them several times since over the years.
Fieg has gone on to collaborate 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 store after 13 some years in the business. The store, Kith NYC, carries brands such as Red Wing, Clarks, Asics, Danner, New Balance, Nike, Gourmet, and Native Footwear. The store, in many ways, acts as a vessel for many of Fieg's limited edition sneaker collaborations, sometimes being the exclusive seller of said shoe upon its release.