Thompson, a 6-foot-8 forward, averaged 13.1 points and 7.8 rebounds per game for the Longhorns.
The 6-foot-3 Joseph averaged 10.4 points per game and shot 41 percent from 3.
Thompson is ranked No. 10 in ESPN.com draft analyst Chad Ford's prospect rankings. Joseph is No. 46. They will be joined in the draft by Texas sophomore Jordan Hamilton, who was looking to hire an agent in April.
Underclassmen had until midnight Sunday to take their name out of the draft pool.