Born near Pevely, Missouri, Hensley attended the public schools and the law department of the University of Missouri.
He was admitted to the bar in 1894 and commenced practice in Wayne County, Missouri. He moved to Bonne Terre, Saint Francois County, Missouri, and continued the practice of law. He served as prosecuting attorney of Saint Francois County 1898-1902.
He moved to Farmington, Missouri, and practiced law.
Hensley was elected as a Democrat to the Sixty-second and to the three succeeding Congresses (March 4, 1911-March 3, 1919). On April 5, 1917, he joined 49 other representatives in voting against declaring war on Germany.
He was not a candidate for renomination in 1918. United States district attorney from March 1919 until he resigned in May 1920.
Reengaged in the private practice of law in Saint Louis, Missouri, until 1936, when he retired and moved to near Pevely.
He died at his summer home in Ludington, Michigan, July 18, 1946. He was interred in Sandy Baptist Cemetery, near Pevely, Missouri.
Member 62d to 65th Congresses (1911-1919), 13th Missouri District. Member firm Hensley, Krause & Hensley.
Children: Robert Thornton, Emily Elyzbeth, Walter Lewis, John Clark.