The Blackbirds won the Northeast Conference tourney on their home court for the second straight year. They extended their home winning streak to 27 games, second-longest in the country behind Kentucky's 52.
It will be the third NCAA trip for LIU-Brooklin. The Blackbirds were eliminated by North Carolina in the opening round last season.
Garner scored 21 points while Julian Bond and Jason Brickman both had 18. The Blackbirds, who won the conference's regular-season title as well, will take a 24-8 record into the NCAA Tournament.
LIU-Brooklyn shot 52 percent from the field and pulled away in the second half after leading by eight at the break.
Lucky Jones had 14 points off the bench for Robert Morris (24-9), the tournament's No. 3 seed.