Kaat attended Hope College in Holland, Michigan, and pitched for the Flying Dutchmen baseball team, before being signed by the Washington Senators as an amateur free agent in 1957.
Kaat would spend all of 1957 and '58 in the minor leagues before breaking into the majors in 1959.
After pitching in 16 games spread out over the next two seasons, Kaat became a permanent member of the pitching staff when the team moved west in 1961 to become the Minnesota Twins.
On July 24, 1963 Jim Kaat threw a complete-game shutout and hit a home run for a 5–0 Twins win over the Indians.
The combination has only happened three times in Minnesota history and Kaat did it twice (with the second coming on October 1, 1970).

On July 23, 1964, he gave up two home runs to Bert Campaneris, who was making his major league debut in the game.
Kaat was a member of the 1965 Twins team that won the American League pennant.
He started three games in the 1965 World Series, matching up with Sandy Koufax on all three occasions, including a complete game victory in Game 2.

His best season was in 1966, when he won a league-leading 25 games.
He finished fifth in the MVP voting and was named the American League Pitcher of the Year by The Sporting News.
The National League's Sandy Koufax won the Cy Young Award by a unanimous vote; it was the last year in which only one award was given for both leagues.
Although his 1967 season was somewhat of a let down after his near Cy Young in 1966 (he finished 16–13 with a 3.04 ERA), he went on a tear in September and nearly pitched the Twins to another World Series appearance – cruising to a 7–0 record with a 1.51 ERA and 65 strikeouts in 65​²⁄₃ innings pitched.
However another shot at a World Series title was not to be as Kaat sustained a season-ending arm injury in the third inning of the second to last game of the season and the Red Sox swept the final two games to win the American League pennant.

Kaat was an All-Star three times (1962, 1966, 1975), and won the Gold Glove Award for defensive skill a record 16 consecutive times (1962–1977).
His record for career Gold Gloves by a pitcher is now second to Greg Maddux's 18.
Kaat used the same baseball glove for 15 seasons.
Although Kaat would pitch a few games a year out of the bullpen, he was primarily a starting pitcher until 1979, when he became a relief pitcher in a season in which he split time between the Philadelphia Phillies and New York Yankees.
He had been traded with Mike Buskey from the White Sox to the Phillies for Dick Ruthven, Alan Bannister and Roy Thomas on December 10, 1975.
With the Cardinals in 1982, Kaat earned his only World Series ring working in four games out of the bullpen in the 1982 World Series.
In 1983 he became the last major league player to have played in the 1950s and the last "original" (pre-Twins) Washington Senator player to retire.
Kaat is one of only 29 players in baseball history to date to have appeared in Major League games in four decades.

At the time of his retirement, Kaat's 25-year career was the longest of any pitcher in major league history.
He is now third all-time, behind Nolan Ryan's 27 seasons and Tommy John's 26 campaigns.
Kaat also set a 20th-century record by playing during the administrations of seven U.S. Presidents – Dwight D. Eisenhower, John F. Kennedy, Lyndon B. Johnson, Richard M. Nixon, Gerald R. Ford, Jr., Jimmy Carter, and Ronald Reagan.
This mark was equaled by Nolan Ryan when he retired after the 1993 Season – the first year of the administration of Bill Clinton.
Ryan first played in the major leagues in 1966, during the Johnson administration.
Kaat attended Hope College in Holland, Michigan, and pitched for the Flying Dutchmen baseball team, before being signed by the Washington Senators as an amateur free agent in 1957. Kaat would spend all of 1957 and '58 in the minor leagues before breaking into the majors in 1959. After pitching in 16 games spread out over the next two seasons, Kaat became a permanent member of the pitching staff when the team moved west in 1961 to become the Minnesota Twins. On July 24, 1963 Jim Kaat threw a complete-game shutout and hit a home run for a 5–0 Twins win over the Indians. The combination has only happened three times in Minnesota history and Kaat did it twice (with the second coming on October 1, 1970).
On July 23, 1964, he gave up two home runs to Bert Campaneris, who was making his major league debut in the game. Kaat was a member of the 1965 Twins team that won the American League pennant. He started three games in the 1965 World Series, matching up with Sandy Koufax on all three occasions, including a complete game victory in Game 2.
His best season was in 1966, when he won a league-leading 25 games. He finished fifth in the MVP voting and was named the American League Pitcher of the Year by The Sporting News. The National League's Sandy Koufax won the Cy Young Award by a unanimous vote; it was the last year in which only one award was given for both leagues. Although his 1967 season was somewhat of a let down after his near Cy Young in 1966 (he finished 16–13 with a 3.04 ERA), he went on a tear in September and nearly pitched the Twins to another World Series appearance – cruising to a 7–0 record with a 1.51 ERA and 65 strikeouts in 65​²⁄₃ innings pitched. However another shot at a World Series title was not to be as Kaat sustained a season-ending arm injury in the third inning of the second to last game of the season and the Red Sox swept the final two games to win the American League pennant.
Kaat was an All-Star three times (1962, 1966, 1975), and won the Gold Glove Award for defensive skill a record 16 consecutive times (1962–1977). His record for career Gold Gloves by a pitcher is now second to Greg Maddux's 18. Kaat used the same baseball glove for 15 seasons. Although Kaat would pitch a few games a year out of the bullpen, he was primarily a starting pitcher until 1979, when he became a relief pitcher in a season in which he split time between the Philadelphia Phillies and New York Yankees. He had been traded with Mike Buskey from the White Sox to the Phillies for Dick Ruthven, Alan Bannister and Roy Thomas on December 10, 1975. With the Cardinals in 1982, Kaat earned his only World Series ring working in four games out of the bullpen in the 1982 World Series. In 1983 he became the last major league player to have played in the 1950s and the last "original" (pre-Twins) Washington Senator player to retire. Kaat is one of only 29 players in baseball history to date to have appeared in Major League games in four decades.
At the time of his retirement, Kaat's 25-year career was the longest of any pitcher in major league history. He is now third all-time, behind Nolan Ryan's 27 seasons and Tommy John's 26 campaigns. Kaat also set a 20th-century record by playing during the administrations of seven U.S. Presidents – Dwight D. Eisenhower, John F. Kennedy, Lyndon B. Johnson, Richard M. Nixon, Gerald R. Ford, Jr., Jimmy Carter, and Ronald Reagan. This mark was equaled by Nolan Ryan when he retired after the 1993 Season – the first year of the administration of Bill Clinton. Ryan first played in the major leagues in 1966, during the Johnson administration.
Jim Kaat