In a 14-year major league career, Kennedy hit .264 with 113 home runs and 628 RBI in 1491 games. Kennedy tied Johnny Bench's NL mark of 40 doubles in a season in 1982. That same year, Kennedy won the Silver Slugger Award. He appeared in four All-Star Games (1981, 1983, 1985, and 1987). He also played in two World Series, with the Padres in 1984 and with the Giants in 1989. Terry and his father, Bob, became the first father and son duo to drive in runs in a World Series when Terry drove in two against the Tigers in 1984 in his first at bat.
Throughout most of his career, Kennedy wore #16, which he was assigned on his first day in major league camp with the Cardinals. When he came to the Orioles, he could not get #16 because veteran pitcher Scott McGregor already had the number, so he wore #15 during his time with them. He reverted to #16 during his time with the Giants, during which he took part in the earthquake-interrupted 1989 World Series.
After his playing days, Kennedy managed, coached, and instructed in the minor leagues for the St. Louis Cardinals, Montreal Expos, Seattle Mariners, Chicago Cubs, Los Angeles Dodgers and San Diego Padres, as well as the Independent Leagues. Kennedy was voted Manager of the Year twice, including Baseball America Manager of the Year in 1998, when he led the Iowa Cubs to a first-place finish.