He attended Denmark Academy in Lee County, Iowa, and Iowa Wesleyan College in Mount Pleasant, Iowa, and was graduated from Ohio Wesleyan College in Delaware, Ohio, in 1859.
Born near Brush Creek Township, Scioto County, Ohio, Walden moved to Iowa in 1852. He settled in Centerville, Iowa (in Appanoose County). After the outbreak of the Civil War, he served in the Union Army, as captain in the 6th Iowa Volunteer Infantry Regiment and the 8th Regiment Iowa Volunteer Cavalry, from May 1861 to May 1865.
He was taken prisoner in an engagement at Newnan, Georgia, in July 1864, known as the Battle of Brown"s Mill during "McCook"s Raid." He later escaped from a prison camp at Charleston, South Carolina, and returned to his company.
By the end of the War he had been promoted to the rank of major. Returning from the War, he taught school, and published the Centerville (Iowa) Citizen from 1865 to 1874.
In 1869 he was elected as Lieutenant Governor of Iowa, starting his term in 1870. In the 1870 Republican district convention for Iowa"s 4th congressional district, Walden upset incumbent Fourth District Congressman William Loughridge in the race for the Party"s nomination for Loughridge"s seat.
However, when Walden ran for renomination in 1872 (in what was reapportioned in 1871 as Iowa"s 6th congressional district), Loughridge turned the tables on Walden, ousting Walden.
After his defeat, Walden engaged in agricultural pursuits and coal mining in Centerville. He returned to Washington, District of Columbia in 1889 when he was appointed chief clerk in the office of the Solicitor of the Treasury, and served until his death in Washington on July 24, 1891. He was interred in Oakland Cemetery in Centerville.
He served as member of the Iowa House of Representatives in 1866 and 1867, and in the Iowa Senate in 1868 and 1869. In 1890 he was again a member of the Iowa House from Appanoose County.