Foyle was born in Canouan, St. Vincent and the Grenadines. At the age of 15, Foyle was adopted by Joan and Jay Mandle, professors at Colgate University. He first attended high school at Cardinal O'Hara Catholic High in Springfield, Pennsylvania. He transferred after sophomore year and attended high school at Hamilton Central School (Hamilton, New York), where he helped the HCS Emerald Knights gain their first two state championships. As of 2016, his 47 points and 25 rebounds in the NYSPHSAA Class D semifinals in 1994 are tied for the most in either statistical category in a state tournament game.
In his official biography, Foyle explained that he enrolled at Colgate University because "he wanted the opportunity to learn the principles of the game in a slower paced setting, where the coach would be able to give him the attention he desired." With the Colgate Raiders, he was the school's all-time leading rebounder and 2nd all-time leading scorer. He left as the NCAA's all-time leader in blocked shots with 492, despite playing only three college seasons (his record was broken by Wojciech Myrda in 2002). He now ranks third all-time, behind Myrda and Jarvis Varnado.
In 1999, Foyle graduated from Colgate magna cum laude with a history degree. Politically motivated, he founded the organization Democracy Matters, which tries to curb the effects of money on politics.
In his NBA career, Foyle averaged 4.1 points and 1.6 blocks per game. He was amongst the 10 highest players in blocks per game three times during his career.
In July 2004, during the offseason, the Golden State Warriors re-signed Foyle to a six-year, $42 million contract. Foyle played very sparingly during the 2006–07 season under new coach Don Nelson, and was waived by the Warriors on August 13, 2007, with three years and $29.2 million remaining on his contract.
On August 23, 2007, Foyle signed with the Orlando Magic for the veteran minimum of $1.3 million. On August 2, 2008, he re-signed with the Magic for another year, also at the veteran minimum.
He was traded to the Memphis Grizzlies on February 19, 2009.
On March 1, 2009 the Grizzlies waived Foyle. Foyle signed with the Orlando Magic on March 23, 2009 for the rest of the season. Later that year, in August, Foyle re-signed with the Magic. However, he underwent arthroscopic knee surgery before the season began, and did not play that season. On August 17, 2010, Foyle announced his retirement. On September 7, 2010, the Magic named Foyle the team's director of player development. He held that position until 2012.
In his spare time, Foyle writes poems and is a political activist. He has reviewed books for HOOP Magazine.
In 2001, he founded Democracy Matters, a non-partisan student organization, as an effort to counteract political apathy on college campuses. The organization's signature issue is campaign finance reform, particularly Clean Elections. Active on over 50 college campuses, Democracy Matters involves hundreds of students and faculty nationwide through teach-ins, letter writing and petition campaigns, educational seminars, and voter registration drives.
In 2005, Foyle founded the Kerosene Lamp Foundation, which serves children in St. Vincent & the Grenadines.KLF website
He played a cameo role of "detective" in the movie The Darwin Awards.
Foyle became an American citizen on March 13, 2007, after being in the U.S. for almost 18 years. He also became a member of the National Basketball Players Association Executive Committee.
On September 24, 2009, Foyle was inducted into the World Sports Humanitarian Hall of Fame. Only eight other NBA players have been inducted into the World Sports Humanitarian Hall of Fame. (Nate “Tiny” Archibald, Vlade Divac, Julius Erving, AC Green, Kevin Johnson, Dikembe Mutombo, David Robinson and Steve Smith).
In 2013, Foyle released his first children's book, called Too Tall Foyle Finds His Game.
In January 2014, Foyle traveled to Spain and Morocco as a SportsUnited Sports Envoy for the U.S. Department of State. In this function, he worked with Ruth Riley to conduct basketball clinics for more than 600 youth from underserved areas. In so doing, Foyle helped contribute to SportsUnited's mission to promote conflict resolution, leadership, greater understanding and inclusion through sport.