Sheriff Jim Hammond said he will not seek another four-year term in the 2022 election.
He said he is backing Chief Deputy Austin Garrett for the post.
The 25-year-old Chattanooga Police Department veteran was named chief deputy at the end of last November and went on the job on Feb. 8.
Sheriff Hammond's law enforcement career has spanned over 50 years. He was the longtime chief deputy to Sheriff H.Q. Evatt before retiring in 1994. He trained law enforcement officers in the Middle East prior to returning home and winning election as sheriff in 2008.