Nunes, a Republican, has represented California's 22nd Congressional District, which includes portions of Fresno and Tulare counties, for ten terms.
He did not specify his plans after he steps down, but a statement from President Donald Trump's company said that he was going to serve as the Chief Executive Officer of the Trump Media and Technology Group.
The 22nd Congressional District district is expected to be one of those affected by California's changed political landscape after the state's redistricting commission recently released drafts of new political maps.
On Monday afternoon, Nunes made the announcement in a letter to his constituents, that said in part:
"It has been my privilege to serve the people of California's San Joaquin Valley for nineteen years in the U.S. House of Representatives... Recently, I was presented with a new opportunity to fight for the most important issues I believe in. I'm writing to let you know I've decided to pursue this opportunity, and therefore I will be leaving the House of Representatives at the end of 2021."
Phil Arballo, the Democrat who ran against Nunes in the 2020 Congressional race and lost, initially issued a succinct statement in response to Nunes' announcement.
He wrote simply:
In a later tweet, he wrote, "Devin Nunes is fleeing from Congress at the end of the month because he would rather cash out and take a cushy gig from Trump than face our movement in a tough reelection campaign. This is now an open seat race and WE WILL WIN."
BREAKING: Devin Nunes is fleeing from Congress at the end of the month because he would rather cash out and take a cushy gig from Trump than face our movement in a tough reelection campaign. This is now an open seat race and WE WILL WIN. Like and RT to join this movement.— Phil Arballo (@PhilArballo) December 6, 2021
Trump Media & Technology group is preparing to launch a social media platform intended to rival Twitter, which blocked Trump's account in January following the deadly storming of the U.S. Capitol.
(with inputs from the Associated Press)