Born on June 10, 1869, in Elyria, Lorain County, Ohio,[1] Kenyon attended Grinnell College and the University of Iowa, then read law in 1891.

[1] Kenyon, relatively unknown in political circles,[3] announced his candidacy for election to the United States Senate by the 1911 Iowa General Assembly.

Considered "a conservative with progressive proclivities,"[3] he sought to wrest the seat away from fellow Republican Lafayette Young, who had been appointed by the governor upon the death of Jonathan P. Dolliver.

[2] Kenyon was re-elected to the Senate in January 1913 (by legislative ballot)[4] and November 1918 (by direct popular election, following ratification of the Seventeenth Amendment to the United States Constitution), defeating Democrat Charles Rollin Keyes, a noted geologist.

[7] Following the Armistice, when Wilson pressed the Senate to support the United States' membership in the League of Nations, Kenyon became a member of the moderate faction known as the "mild reservationists," who allowed for the possibility of membership so long as the treaty were amended to address a specified list of reservations held by those senators and pursued compromise solutions.

[11] Kenyon was nominated by President Warren G. Harding on January 31, 1922, to a seat on the United States Court of Appeals for the Eighth Circuit vacated by Judge Walter I.

[1] In 1926, Kenyon wrote the Eighth Circuit's ruling in the principal civil suit arising from the Teapot Dome scandal.

In January 1932, when Justice Oliver Wendell Holmes retired, Kenyon's name was again included on short lists of potential successors,[17] but this time Hoover selected New York Court of Appeals Judge Benjamin Cardozo.