Nunn was born in 1995 to parents Melvin Nunn Jr. and Kimberly Harris in Chicago, Illinois. He attended high school at Simeon Career Academy in Chicago for four years, where his number (20) was retired after he led the school to four consecutive state titles. During his time at Simeon, Nunn shared the court with fellow future NBA player Jabari Parker. Nunn received scholarship offers as early as his freshman year and had one point even committed to Texas A&M, but he later de-committed and chose Illinois over the likes of Marquette, Memphis and Ohio State. He spent three years at Illinois before transferring to Oakland, where he finished his degree in Integrative Studies. Nunn has two sisters, Kendyl Nunn and Sarafina Benson. He also owns a marketing business called NunnBetter Group. You can follow him on Twitter and Instagram (@nunnbetter_).