He was a six-time United States congressman from Virginia's 9th congressional district from 1907 to 1923 and served as the presidential secretary to President Calvin Coolidge.

[4][5] Slemp served as Commandant of Cadets at the Marion Military Institute for one year, after which he was hired as the second principal of the Stonega Academy in Big Stone Gap (1893–1895).

In 1901, after Slemp was admitted to the Virginia bar, he resigned his position at the institute to set up a law practice in Big Stone Gap.

As the leading Republican in the Old Dominion, he faced a difficult battle for re-election in 1910, after Democrats persuaded Henry C. Stuart to run against him, and used the slogan "Redeem the District."

[14] An article in the nationally syndicated Pittsburgh Courier reported that "The Associated Negro Press has been informed from a number of sources that Slemp is a member of the Ku Klux Klan and a strong sympathizer with that nefarious organization.

Slemp often maintained a local residence with siblings, and remained a prominent member of the southwest Virginia community and political scene until his death.

The "Lonesome Pine Regional Library" (which serves Lee, Dickenson, and Wise Counties) has received support from the foundation, and its branch in Big Stone Gap is named in Slemp's honor.

It hosts folk events and concerts throughout the year, as well as a wintertime Christmas tree exhibit highlighting local charities and crafts.

The Slemp Scholarship, named in honor of the late congressman, is awarded to outstanding college students who graduated from schools in Lee, Scott, and Wise counties, Virginia.

The United States Post Office and Courthouse at Big Stone Gap, Virginia, is named the C. Bascom Slemp Federal Building, although regularly scheduled court sessions there ceased during Masssive Resistance.