Aparicio, born in Maracaibo, Venezuela broke into the major leagues in 1956 with the Chicago White Sox. He played for them until 1963 when he was traded to the Baltimore Orioles and played there from 1963 to 1967. After the end of the 1967 season Aparicio was traded back to the White Sox where he played from 1968 to 1970. After the end of the 1970 season he was traded to the Boston Red Sox where he played from 1971 to 1973. The Red Sox released him before the start of the 1974 season.
Aparicio's biggest accomplishments were being elected to the Baseball Hall of Fame in 1984, winning the American League Rookie of the Year award in 1956, being a 10 time member of the American League All-Star team, being awarded the American League shortstop Gold Glove fielding award 9 times, leading the American League a record 9 straight times in stolen bases, stealing 506 bases in his career and being on the 1966 World Series winning Orioles team.
At his retirement, Aparicio was the all-time leader for most games played, assistss and double plays by a Major League Baseball shortstop and the all-time leader for putouts and total chances by an American League Baseball shortstop.