The 6-foot-8 Toro averaged 6.5 points and a team-high 7.0 rebounds in 18.4 minutes per game for the Colonials last season. After spending four years at George Washington, he will be eligible to play for the Red Storm immediately.
Heading into his second season at St. John's, coach Mike Anderson hopes Toro can help fill out a thin front line.
Toro was born in Puerto Rico and played high school ball in New Jersey. He averaged 6.5 points and 6.2 rebounds in 99 career games with George Washington.
"Arnaldo is a mature player who brings plenty of experience to our program. We believe his physicality and ability to extend the floor will fit our brand of basketball well," Anderson said in a news release.
Toro had a career-high 24 rebounds against American last season, equaling an Atlantic 10 record. He played in seven games, all starts, as a junior in 2018-19 before being sidelined by an injury.
St. John's went 17-15 in Anderson's first season, including 5-13 in Big East play. The Red Storm won their conference tournament opener against Georgetown last month and were leading top-seeded Creighton at halftime the following day when the rest of the event was canceled due to the coronavirus.