The school said a news conference to introduce Lavin would be held Wednesday.
Lavin has been an analyst for ESPN since UCLA fired him in 2003. He had a 145-78 record with UCLA, leading the school to the NCAA tournament's round of 16 five times. The Bruins reached the final eight in 1997, his first season.
St. John's, which fired Norm Roberts after six seasons, has not been to the NCAA tournament since 2002.
The Red Storm lost to Memphis in the first round of the NIT to finish the season at 17-16, giving Roberts an 81-101 record with the school.
St. John's returns all five starters and 94 percent of its scoring from last season's team.
Georgia Tech coach Paul Hewitt rejected an offer from St. John's last week. Al Skinner, who was fired by Boston College on Tuesday, also was interviewed.
Lavin was fired by UCLA after going 10-19, his only losing season and the school's first in 55 years. It was the only season in which one of Lavin's UCLA teams did not win at least 20 games.
He was succeeded by former Pittsburgh coach Ben Howland.
Lavin, who had five years remaining on his contract when he was fired, fell into the job when Jim Harrick was fired in November 1996 — only a week before the season began and 19 months after the Bruins won their 11th national championship. With Harrick assistants Mark Gottfried and Lorenzo Romar already having taken head jobs, then-athletic director Peter Dalis promoted Lavin from unproven assistant to head coach.
His teams at UCLA beat four No. 1-ranked teams, but in his final season, the Bruins had a then-record 10 losses at Pauley Pavilion and the average attendance of 8,348 in the 12,819-seat arena was the lowest since 1993.
Ten of UCLA's national championships were won under coach John Wooden in the 1960s and 1970s. The other was under Harrick in 1995 — when Lavin was the No. 3 assistant.