He was named the American League's Most Valuable Player in 1943 after anchoring the team's pitching staff with 20 wins and only 4 losses as New York won its third consecutive pennant; his 1.64 earned run average in that season was the lowest by any major league pitcher between 1920 and 1967, and remains a Yankees team record. In eleven seasons, he never suffered a losing record; with a total of 109 wins and 43 losses, his career winning percentage of .717 is the highest of any pitcher with at least 100 victories since 1876.
Chandler was born in Commerce, Georgia to Leonard Ferdinand Chandler (1871–1942) and Olivia Catherine Hix (1872–1957), and attended the University of Georgia. He played football as a halfback, throwing a touchdown pass to help defeat Yale in a 1929 game dedicating a new stadium. He also pitched for the baseball team and competed on the track team. He was a brother of the Alpha Gamma Rho fraternity and graduated with a degree in agriculture. He spent five seasons in the Yankees organization after signing with the team, his favorite since boyhood. Chandler finally made his major league debut at age 29 on May 6, 1937, and went 7-4 that season with a 2.84 ERA and six complete games (including two shutouts). The following year he was 14-5, and in 1939 he was 3-0 in 11 relief appearances. Although the Yankees won the World Series in each of those years, Chandler did not appear in the postseason. Bothered by injuries during his early career, after records of 8-7 and 10-4 in 1940 and 1941 he improved further to 16-5 in 1942, finishing third in the AL with a 2.38 ERA and earning his first of four All-Star selections. He was the All-Star Game's winning pitcher in 1942. Chandler had one start in the World Series each year, but lost both times, as the Yankees won in 1941 and lost in 1942.
His greatest year came in 1943. In addition to his outstanding ERA, he led the league with 20 wins in 30 starts, as well as 20 complete games and five shutouts. In 253 innings pitched, he gave up 46 earned runs, allowing only five home runs. Chandler's 134 strikeouts were third in the league, and equalled his combined total of the previous two seasons. He made the AL All-Star team for the second time. Chandler finally had a successful World Series, pitching two complete game victories, including a shutout in the final Game 5, as the Yankees defeated the St. Louis Cardinals. Winning the MVP award, he beat out Luke Appling of the Chicago White Sox. Chandler remains the only Yankee pitcher to win the Most Valuable Player award.
After one start in 1944, he entered World War II military service with the Army for nearly all of the next two seasons. He returned in 1946 with another All-Star season, going 20-8 with a 2.10 ERA (2nd in the league to Hal Newhouser) and a career-high 138 strikeouts. That year he also had 20 complete games for the second time in his career. He earned his last All-Star selection in 1947, but finished the year with only a 9–5 record as injuries ended his career at age 40. He pitched for the last time in the historic 1947 World Series against the Brooklyn Dodgers, pitching two relief innings in a Game 3 loss. In four World Series, he had a 2–2 record with a 1.62 ERA, 16 strikeouts, and 1 shutout.
Over his career Chandler was 109-43 in 211 games (109 complete, 26 shutouts), with a 2.84 ERA. He had 614 career strikeouts and gave up 64 home runs and 1327 hits. As a hitter, he had a batting average of .201, with a .234 on-base percentage; he had 110 hits in 548 at bats in his career, and on July 26, 1940 had two home runs including a grand slam. He later managed in the minor leagues, became pitching coach with the Kansas City Athletics in 1957–58, and scouted for several teams before retiring in 1984. He was inducted into the Georgia Sports Hall of Fame in 1969 and into the Franklin County Sports Hall of Fame in 1997.