Thomas will serve as Sorrell's assistant principal.
Thomas and Sorrells are both returning to Fayetteville where they were Lincoln County football players, teachers, and coaches.
Thomas is a high school legend in Fayetteville and a former Ohio Valley Conference Defensive Player of the Year in 1988 as a linebacker at MTSU.
After a brief stint on the Lincoln County High School football staff Thomas became the head coach at Lee High School in Huntsville, Ala.
Thomas would leave Lee and move to LaVergne where he was named the 2005 Region 4-5A Coach of the Year.
Thomas came to Marshall County in 2007 and sported an overall 18-15 record in his three seasons at the helm of the Tigers, going 17-13 in the regular season and 1-2 in the TSSAA playoffs.
MCHS went a dismal 1-9 last season after back-to-back 8-2 seasons under Thomas.
Thomas' only playoff win came in his first season in 2007 when the he prevailed 21-14 in a comeback win at Jackson Southside in the first round.
The Tigers lost at David Lipscomb the following week 32-14 and suffered a first round 24-20 loss at Lexington in the first round in 2008.
MCHS Athletic Director Kevin McGehee, who found out Friday afternoon about Thomas' resignation said, "Coach Thomas has resigned and will become assistant principal in Fayetteville. I do not know what we are going to right now; we are in kind of a mess. Until we find a football coach the current assistants will run the program."
According to McGehee, the Marshall County Board of Education will post the head coaching vacancy on July 5 and the notice will remain up for the required seven days.
TSSAA football activities are in a dead period until July 12.