In 1945, Chandler left the Senate to succeed Kenesaw Mountain Landis (1866-1944), a [[Segregation|segregationist]], as commissioner of baseball. In this capacity, Chandler approved the contract of [[Jackie Robinson]] with the former [[Brooklyn Dodgers]] and hence [[Segregation|desegregated]] baseball. The baseball owners had all opposed admitting Robinson into the league, but Chandler overruled them. Chandler established the first pension fund for MLB players financed by [[radio]] rights on the [[World Series]]. The baseball owners, influenced by Dodgers manager Leo Ernest Dorocher (1905-1991), whom Chandler derided for alleged times to [[gambling]], did not renew his contract in 1951.<ref>Chandler, Happy | Baseball Hall of Fame, accessed July 31, 2021.</ref><ref name=utube/>
Following his term as commissioner, Chandler returned to Kentucky and won a second term as governor in 1955. He presided over the racial integration of state schools and established a medical school at the [[University of Kentucky]], renamed the Chandler Medical Center. Following his second term as governor, his political influence began to wane as he made three more unsuccessful runs for governor in 1963, 1967 (when the Republican [[Louie B. Nunn]] was elected), and 1971, when the office passed to the Democrat Wendell Hampton Ford (1924-2018), later one of the state's two U.S. senators.
Chandler's support in 1987 for dark-horse gubernatorial candidate Wallace Glenn Wilkinson (1941-2002) paid off as Wilkinson resisted calls to remove Chandler from the University of Kentucky board of trustees following the former governor's use of a racial expression at a 1988 board meeting. Chandler was first appointed to the trustess by Louie Nunn, whom Chandler supported In the 1967 election. In 1968, he was considered as a vice-presidential running mate got [[alabama]]'s [[George Wallace]] third-party campaign, but the two could not resolve their "racial differences."<ref>Andy Mead and Jim Warren, "Kentucky's "happyHappy" Chlander Chandler Dies, ''Lexington Herald-Leader,'' June 16, 1991, p. A-1.</ref>
Chandler often made numerous public appearances and remained active in state politics and events. He often sang the state's song, '"My Old Kentucky Home" by Stephen Collins Foster at public gatherings such as UK sporting events. His rendition often brought tears to listeners.<ref name=utube>{{cite web|url=Ahttps://www.Bbing. "Happy" Chandler's Old Kentucky Home - YouTubecom/videos/search?q=happy+chandler+singing+my+old+kentucky+home&view=detail&mid=4D0F9DB9176C379841F44D0F9DB9176C379841F4&FORM=VIRE|title=A. B. "Happy" Chandler's My Old Kentucky Home|publisher=You Tube|accessdate=July 31, 2021}}</ref>
Chandler died a month before his ninety-third birthday; at the time, he was the oldest living former Kentucky governor and the earliest serving former governor. In 1982, he was the oldest person inducted into the Baseball Hall of Fame.<ref name=nyt>{{cite web|url=https://www.nytimes.com/1991/06/16/obituaries/ab-happy-chandler-92-dies-led-baseball-during-integration.html|title=A.B. (Happy) Chandler, 92, Dies; Led Baseball During Integration|author=Robert M. Thomas, Jr.|publisher=''[[The New York Times]]''|date=June 16, 1991|accessdate=July 31, 2021; under pay wall}}</ref>