Haynie is a native of Buffalo, New York. He started primarily as a sample-driven hip-hop producer and got his first big break after handing off a beat CD to now-deceased Detroit rapper Proof. He then began producing for various members of Eminem’s Detroit camp, as well as New York City rappers Raekwon, Cormega, and C-Rayz Walz. He relocated to New York City and got his start as a hip hop producer in the early 2000s, collaborating with rappers Obie Trice, Ghostface Killah, The Roots, Cormega, M.O.P.,Rhymefest, and AZ. His career grew and, by the second half of 2000's first decade, he had worked with Ice Cube, Slaughterhouse, Eminem, Kanye West and Kid Cudi. Haynie remixed Michael Jackson's 1972 song, "Maria (You Were the Only One)", for the 2009 album Michael Jackson: The Remix Suite.
Haynie was nominated for the 2010 Grammy Award for Album of the Year for Eminem's Recovery. He co-produced Kanye West's 2010 single, "Runaway", and expanded into indie music and pop music, working with Lana Del Rey, Bruno Mars and Fun. Haynie produced Lana Del Rey's 2012 album, Born to Die, which debuted on the Billboard 200 chart at number two, and at number one in Britain, Germany, Ireland, Switzerland and Austria, respectively. Alongside Jeff Bhasker, Haynie also produced Fun's second album Some Nights(2012). Haynie also co-wrote Lady Antebellum's 2013's single, "Compass".