Long-standing Cornish MP George Eustice is to step down at the next election.
His Camborne and Redruth seat is one of Labour's top targets in the next General Election.
The former Environment Secretary says he wants to pursue a career outside of politics and has vowed to work tirelessly for his constituents over the final two years of his term.
Mr Eustice said: "By the time of the next election, I will have been in politics for 25 years, including almost 15 years as a Member of Parliament.
"I will also be 53 and I want the opportunity to do a final career outside politics so have decided not to seek re-election."
He said the decision had been "a difficult one".
Mr Eustice, who has been MP for Camborne, Redruth and Hayle since 2010, said: "I feel a deep bond to the area where my family have lived for over 400 years and it had been an honour to represent my home towns, but it is important that the Conservatives are able to select a new candidate in good time.
He said: "There are still almost two years left of the current parliament and I will be doing my utmost throughout that time to help my constituents and deliver for Cornwall."
Brexit supporter Mr Eustice was secretary of state for environment, food and rural affairs under Boris Johnson from February 2020 until September 2022 and regularly accompanied Mr Johnson on his visits to Cornwall.
Mr Eustice, who grew up at his parent’s farm, Trevaskis Farm near Connor Downs, was first elected in May 2010 with a majority of 66 votes over the Liberal Democrat incumbent Julia Goldsworthy.
In his first speech at the House of Commons, he said: “It is a special honour for me to represent my home town. I was brought up between Camborne and Hayle, in Cornwall, and my family have lived and worked in the area for more than 400 years.
"When one has such deep roots in a constituency, one feels a special responsibility for its long-term future."
Later in the same speech he said his number one priority was economic regeneration.