Mack, who also drew scholarship offers from UConn and South Carolina, among other programs, is the No. 77 player in the class of 2015, according to rankings on the recruiting website Rivals.com.
The 6-foot-6 Mack joins four-star shooting guard Kenny Williams as members of the 2015 class who have committed to the Rams.
This season VCU welcomes in a four-man recruiting class highlighted by four-star small forward Terry Larier.
The Rams went 26-9 last season.