Drummond, 6-foot-10, averaged 10 points and 7.6 rebounds a game for the Huskies last season. He had a Connecticut freshman record 10 double-doubles.
He is projected as a potential lottery pick in the draft, which is scheduled for June 28.
"My family and I feel that this is the right time for me to take the next step in my basketball career," Drummond said Friday. "It has always been a goal of mine to compete against the world's best players and that is one of the big factors for me in making this decision.
"Although I was only at UConn for one year, the experience I gained playing against the best competition at the college level greatly helped me prepare for what I will face as I pursue a career as a professional."
Earlier this week, Connecticut sophomore Jeremy Lamb declared himself eligible for the NBA draft.