Born in Wilder, Idaho, Batt was the fifth and youngest child of John and Elizabeth Karn Batt.
Batt served sixteen months in Colorado at Lowry Field near Denver as a clerk, discharging veterans before being discharged himself. He then returned to the University of Idaho and studied chemical engineering, lived in the dorms, and led a dance band, playing clarinet and tenor saxophone. (Half a century later as governor, Batt played with Lionel Hampton in Moscow at the jazz legend's UI festival.)
A year later in January 1948, he eloped with Jacque Fallis of Spokane, a member of the Delta Delta Delta sorority. The newlyweds had to leave school a month later when Batt's 66-year-old father was involved in a serious automobile accident which left him with limited strength and speech. Though the young Batts initially hoped to return to college, economic circumstances changed their plans and they reluctantly did not.
Before becoming governor, Batt had been a Republican politician in Idaho for thirty years, serving in the state legislature (house 1965–67, state senate 1967–79) and as the 35th lieutenant governor from 1979 to 1983. He ran for governor in 1982 and was defeated in a close race by the Democratic incumbent, John Evans. The election was so close that at least one television network declared Batt the winner on Election Night.
Batt returned to the state senate with victories in 1984 and 1986, then resigned in the spring of 1988 to sit on the three-member state transportation board, appointed by Governor Andrus.
Batt was elected chairman of the Idaho Republican Party in January 1991, and after a successful two years, he stepped aside in April 1993 to re-enter electoral politics in 1994.
Batt won the Republican gubernatorial primary in 1994 with 48% of the vote, and defeated state attorney general Larry EchoHawk in the general election 52% to 44%, for the first GOP victory for governor in 28 years. Despite high popularity, he chose to serve only one term, citing his age, and left office at age 71. Succeeding Batt, Kempthorne won two terms and Butch Otter three terms, giving the Republicans six consecutive wins through 2014. Among Batt's more notable accomplishments as governor was pushing through worker's compensation for agricultural workers and negotiating a pact limiting nuclear waste storage in Idaho.
Batt was a Presidential Elector for United States presidential election, 2000 for George W. Bush in Idaho.
Batt has self-published two books since leaving office, a memoir titled The Compleat Phil Batt: A Kaleidoscope in 1999, and a compilation of humorous stories, Life as a Geezer, in 2003. Batt, who has a gay grandson who lives out of state, supports Add The Words.