The 38-year-old Roberts moves to St. John's from Kansas, where he was an assistant on the staff of Coach Bill Self.
Roberts succeeds Mike Jarvis, who was fired in December. The Red Storm had a 6-21 record last season, one of the worst in the school's history.
"This is coming home," Roberts, a New York city native, said at a news conference."It's very exciting to be coaching in New York again, at a place where I always dreamed of doing the job."
Other candidates for the St. John's job had been DePaul Coach Dave Leitao and former North Carolina Coach Matt Doherty.
Roberts worked for Self at Oral Roberts, Tulsa and Illinois before going to Kansas.
"We are so very happy for Norm," Self said. "He's an excellent recruiter, he's an excellent coach and he
conducts his business in a manner which any university would be proud. He has a unique way of getting close to players quickly."