Villanueva is a spokesman for the NAAF (National Alopecia Areata Foundation),[3] and received the February 2006 Community Assist Award from the NBA for his work with the organization.

[8] During his freshman year, Villanueva attended Newtown High School in Queens, New York, where he was a teammate of future NBA player Smush Parker.

He spent his next three years at Blair Academy in Blairstown, New Jersey, where he played with another future NBA player, Luol Deng.

He entered the 2003 NBA draft, but withdrew his eligibility so he could play college basketball for the University of Connecticut.

Villanueva declared for the 2005 NBA draft following his sophomore season, thus forgoing his final two years of college eligibility.

[12][13] On April 9, 2008, Villanueva scored a season-high 38 points and made a career-high seven 3-point shots during a loss against his former team, the Raptors.

[14] In March 2009, Villanueva was reprimanded by Bucks coach Scott Skiles for posting a message on his Twitter account during halftime of the Bucks–Celtics game.

He was described by Pistons President of Basketball Operations Joe Dumars as "a versatile big man who can play in the post and score from the perimeter as well."

[21] On January 2, 2013, Villanueva was fined $25,000 by the NBA for delivering a flagrant foul to Sacramento Kings guard Isaiah Thomas the previous night.

Villanueva represented the United States at youth levels but in 2009, he switched sports citizenship to the Dominican Republic.