Braun was born in New York City to Conservative Jewish parents, Ervin and Susan (née Schlussel) Braun. Ervin's parents "had barely escaped" the Holocaust, and lived in Hungary until 1956. Shortly before the Soviet Union intervened to suppress the Hungarian Revolution, they fled to the United States. Ervin grew up in Queens, and became a dentist; Susan Schlussel Braun was an orthodontist. After the couple married, they settled in Greenwich, Connecticut.
Braun has four siblings: Liza, Cornelio, Sam, and Adam. Adam Braun is the founder of Pencils of Promise, a charitable organization focused on building schools in the developing world.
Braun grew up in Cos Cob, Connecticut and attended Greenwich High School where he was elected class president. He played basketball from age 13 to 18 in the Amateur Athletic Union with the Connecticut Flame. When Braun was 17, his parents adopted Sam Mahanga and Cornelio Giubunda, former members of the Mozambique junior-national team. Without a team at the time because of an athletic-basketball program that had soured, Ervin Braun recruited them for an all-star tournament. Mahanga and Giubunda became stars in the Greenwich High basketball team despite being heckled by fans—an experience that affected the Brauns tremendously. While at Greenwich High School Braun entered a video-documentary contest for National History Day with a 10-minute piece titled The Hungarian Conflict about Jews in Hungary before, during, and after the Holocaust. The film won in regional and state competitions and then placed third overall. A member of Braun's family sent the film to director Steven Spielberg's office, who, in turn, submitted Braun's video to the United States Holocaust Memorial Museum. Braun has said Spielberg's affirmation was one of the most inspirational moments in his life.
Braun went to college at Emory University in Atlanta where he also played college basketball until his sophomore year. After Jermaine Dupri asked him to become the head of marketing at his label, So So Def, Braun reportedly dropped out of university without a degree.