Guokas played on the 1967 Philadelphia 76ers team, featuring Wilt Chamberlain, Hal Greer, Chet Walker and Billy Cunningham, that ended the eight-year championship streak of the Boston Celtics. He also played with the Buffalo Braves, Chicago Bulls, Cincinnati Royals, Houston Rockets, and Kansas City Kings, all of the NBA. In the 1972-73 season, Guokas finished second (to Chamberlain) in the NBA in field goal percentage with a 0.570 mark.
Guokas later coached the Sixers as well as the Orlando Magic, compiling a 230-305 career record. He currently works as a TV and radio analyst for the Magic. He was also a Color commentator for the NBA on NBC during the 1990s and was a color commentator for the Cleveland Cavaliers for a number of years in the late 1990s.
Matt and his father, Matt Guokas, Sr., were the first father-son duo to both win NBA championships as players; this feat has since been repeated by Rick Barry (with the 1975 NBA champion Golden State Warriors) and Brent Barry (with the 2005 and 2007 NBA champions San Antonio Spurs).