Allott was born in Pueblo, Colorado, to Bertha (née Llewellyn) and Leonard J. Allott; his maternal grandparents were Welsh and his paternal grandparents were English.

Allott was also an athlete in his youth, winning the 440 yd hurdles at the 1929 United States championships.

During World War II, Allott served as a major in the United States Army Air Forces from 1942 to 1946.

Allott voted in favor of the Civil Rights Acts of 1957,[4][5] 1964,[6] and 1968,[7] as well as the 24th Amendment to the U.S. Constitution,[8] the Voting Rights Act of 1965,[9][10] and the confirmation of Thurgood Marshall to the U.S. Supreme Court,[11] while Allott did not vote on the Civil Rights Act of 1960.

Paul Weyrich and George Will worked on his Senate staff.