Toppin is the younger brother of former Dayton forward Obi Toppin, last season's Wooden Award winner and consensus Player of the Year.
Toppin, a 6-foot-8 forward, averaged 5.1 points and 3.9 rebounds in a reserve role at Rhode Island last season. He started four games. He's an athletic prospect with developing range from the perimeter.
Barring a change in NCAA transfer regulations, Toppin will have to sit out next season before having three years of eligibility remaining in 2021-22.
Kentucky is losing eight of its top nine players from last season, with six players leaving for the NBA draft, Johnny Juzang transferring to UCLA and Nate Sestina using up his eligibility. Keion Brooks is the lone returnee for John Calipari.
However, Calipari will bring in the nation's No. 1 ranked recruiting class, led by three five-star guards. Toppin is the second transfer the Wildcats have landed this spring, following Creighton graduate transfer Davion Mintz. Kentucky is also considered one of the favorites for former Purdue big man Matt Haarms, the top available transfer.