Izzo was impressed that Forbes scored 22 points against Kentucky last season, a game in which he made seven 3-pointers.
Forbes will be eligible to play in the 2015-16 season along with another transfer, former West Virginia high-scoring guard Eron Harris, after both sit out next season. The 6-foot-3 Harris, who is from Indianapolis, averaged 17.2 points last season and also considered Michigan and Purdue.
The 6-foot-3 Forbes reunites with Lansing Sexton High School teammate Denzel Valentine. Forbes led his team in scoring last season and made 2.5 3-pointers per game, ranking second in the Horizon League. He averaged 12.7 points as a freshman and was the conference's newcomer of the year.
Information from the Associated Press was used in this report.