They made their announcements Tuesday.
A source close to the situation previously told ESPN that Stauskas would leave for the draft.
Stauskas, who is from Mississauga, Ontario, had a breakout season in 2013-14, averaging 17.5 points while shooting 44 percent from 3-point range and 82 percent from the free throw line.
"I heard from the advisory board in the middle of last week, a couple days after that I really decided,'' Stauskas said. "The information I got from them was kind of what I wanted to hear.''
Robinson, whose dad played in the NBA, needed a little longer to decide whether to stay or go.
"I really didn't make my decision until last night,'' he said Tuesday.
Sophomore forward Mitch McGary has not decided if he will stay in school or go pro. He was not made available for interviews after his teammates had a news conference.
Information from ESPN's Jeff Goodman and The Associated Press was used in this report.