Deng was born in Wow, Sudan, and has since lived in Egypt, the UK, as well as the United States. Deng has represented England at Under-16 and Under-19 level, and was an ambassador for the London 2012 Olympic Games bid.
In 2003, Deng was widely considered to be the second most promising player among U.S. high school seniors, after only LeBron James. He attended Blair Academy in New Jersey, along with Charlie Villanueva, another NBA draftee. Deng opted to play one season of college basketball for Duke University, after which he was chosen seventh overall in the 2004 NBA Draft. The pick was made by the Phoenix Suns, but Deng was immediately traded to the Chicago Bulls as part of a previous arrangement. In Chicago, he wears number 9 and plays the small forward position. Deng suffered a season-ending wrist injury late in his rookie season but still made the NBA All-Rookie First Team. As a sophomore, he posted strong performances throughout March and April to help the Bulls earn their second consecutive playoff berth.
- Deng's older brother was taught to play basketball by NBA legend Manute Bol. Bol, also a native of Sudan, has been a mentor to Deng throughout his professional career.
- Deng reportedly grew an inch (to 6'9") between his first and second seasons in the NBA.
- Deng has a seven foot wingspan.