His name is spelled Isiah but pronounced the same as the more common Isaiah /aɪˈzeʌ/. He was also referred to by the nicknames Zeke, Cuts (for the numerous cuts over his eyelids) and Baby-faced Assassin.

Isiah Thomas played for Indiana University and was named to the Olympic team, although the U.S. boycotted that year's games in Moscow in protest of the invasion of Afghanistan by the Soviet Union. He earned All-Big Ten honors in 1980, becoming the first freshman in conference history to accomplish the feat. In 1981 in his sophomore season, Thomas was an All-American, averaging 16 points and 5.8 assisits as he led the Hoosiers to a 26-9 national championship season. In the title game at Philadelphia, he scored a game-high 23 points in Indiana's 63-50 victory over North Carolina. He left Indiana for the National Basketball Association in 1981. He earned a bachelor's degree from IU in criminal justice several years later, as he promised his mother in writing that he would when he left college early to enter the NBA draft.

In the 1981 NBA Draft, The Detroit Pistons chose Thomas and signed him to a four-year $1.6 million contract. With their rookie point guard averaging 17 points and 7,8 assists, the Pistons improved by 18 games (from 21-61 in the 1980-81 NBA season to 39-43 in the 1981-82 NBA season). Thomas made the All-Rookie team after starting for the East in the 1982 NBA All-Star Game.

In 1983, Thomas made the All-NBA second-team when he averaged 22.9 points,which would be his career high. The following year, under new coach Chuck Daly, he averaged 21.3 points and 11.1 assists and was voted first-team after leading the Pistons to a 49-33 record, the franchise's first winning season in seven years.

In making all-league first team again in 1985, Thomas recorded 1,123 assists (13.9 average), breaking the NBA record of 1,099 set by Detroit's Kevin Porter in 1979.

Thomas, a 6-1, 182 pound point guard, ranks as one of the 50 greatest players of all-time. From 1981 to 1994 Thomas had an exceptional career with the Detroit Pistons. He was a 12-time NBA All-Star, and is the Pistons' all-time leader in both points and assists. Thomas ranks fourth in NBA history in assists (9,061, 9.3 apg) and ranks ninth in NBA history in steals (1,861). Thomas was known for his dazzling dribbling ability as well as his uncanny ability to drive to basket and score on much bigger players.

With fellow Detroit Bad Boys teammates Joe Dumars, Rick Mahorn, Vinnie "the Microwave" Johnson, Dennis Rodman, and Bill Laimbeer, he led the Pistons to NBA titles in 1989 and 1990, and was voted NBA Finals Most Valuable Player in 1990 after averaging 27.6 points per game, 7.0 assists per game, and 5.2 rebounds per game in the series. He once scored 16 points in 93 seconds in a 1984 NBA Playoffs game against the New York Knicks. In Game 6 of the 1988 NBA Finals, Thomas set an NBA Finals record by scoring 25 points in a quarter, while playing on a severely injured ankle.

In 1992, Thomas was passed over by the U.S. Olympic Basketball Team (popularly known as the Dream Team) when John Stockton was picked instead of him. At the time, Thomas had two championships to his credit. Only two members of the team had more: Magic Johnson (5) and Larry Bird (3). Some feel he was snubbed by the team because Michael Jordan did not want Thomas on the same team as him due to their bitter rivalry in several playoff battles, or possibly because Jordan harbored ill will against Thomas due being passed over himself at the 1985 NBA All-Star Game, for which he felt Thomas was responsible.