William Squire Kenyon was born on June 10, 1869, to the Rev. Fergus Lafayette and Harriet Squire Kenyon in Elyria, Ohio. His family moved to Iowa in 1878. Although his father had hoped that he would go into the ministry, William Kenyon chose to study the law. He attended Grinnell College, and received an LL.B. from the University of Iowa in 1890. The following year he was admitted to the bar. Kenyon began his legal career in Fort Dodge, Iowa where he married Mary Duncombe, in 1893. Two years after graduating from law school he became the prosecuting attorney for Webster County. At age thirty-one he was elected District Court judge, a position from which he resigned after two years because of the low salary. He next became the general counsel for the Illinois Central Railroad.

It was his service as special assistant to the U.S. Attorney General George W. Wickersham prosecuting packing houses and railroad rebate cases that placed him in the political spotlight. In 1911, Kenyon was appointed to fill the unexpired term left in the U.S. Senate following the death of Jonathan P. Dolliver. Kenyon was twice reelected to the Senate as a progressive Republican. He was one of the senators that opposed U.S. entry into World War I. However, after war was declared and our troops mobilized, Kenyon became an ardent supporter of the U.S. war effort.

In 1922, Kenyon resigned his senate seat to accept an appointment by President Warren Harding to serve on the Federal Circuit Court of Appeals bench. His most famous judgement involved revoking the Teapot Dome oil leases (part of the infamous Teapot Dome scandal). President Coolidge twice offered Judge Kenyon posts in his Cabinet and the judge declined both times in favor of remaining on the bench. He was also seriously considered for the Vice Presidency. In 1929, President Hoover appointed him to the National Commission of Law Observance and Enforcement (Wickersham Commission).

Judge William Squire Kenyon died of a heart attack on September 9, 1933.