Dominic Raab, who resigned from cabinet last month after a bullying inquiry, will stand down as an MP at the next general election.
The former deputy prime minister and justice secretary confirmed his exit plans on Monday night.
Mr Raab quit Rishi Sunak’s cabinet last month over bullying allegations from civil servants.
An independent investigation by Adam Tolley KC found he had acted in an intimidating and aggressive way with officials in behaviour that could have amounted to bullying.
Mr Raab will not contest his Esher and Walton seat, which he has held since 2010, at the next election, due by January 2025.
Liberal Democrat leader Sir Ed Davey told LBC on Tuesday morning: “He knew he was going to lose.”
Sir Ed added: “We’ll be working every day to earn the trust of people in Esher and Walton. It’s not just about Dominic Raab, it really is about the whole Conservative Party.”
The Surrey constituency, which Mr Raab won by just 2,743 votes at the 2019 election, is a key target for the Liberal Democrats at the next national poll.
He joins a slew of senior Tories, including former chancellor Sajid Javid and ex-environment secretary George Eustice, announcing their exit plans amid a polling slump.
I have become increasingly concerned over the last few years about the pressure the job has placed on my young family
Former health secretary Matt Hancock, who was a Conservative until he lost the whip over his I’m A Celebrity appearance, and Dehenna Davison, seen as a rising star in the Tory party, are also among around 30 Tories to be quitting the Commons.
In a letter to the chairman of his local Conservative Association, seen by the Telegraph, Mr Raab reportedly cited concerns about the pressure on his family as being behind his decision.
“I have become increasingly concerned over the last few years about the pressure the job has placed on my young family,” he wrote in the letter dated May 19, according to the newspaper.
“I will continue to carry out all my responsibilities to my constituents, and provide every support in campaigning, so that we win here next year – which I am confident we can do under this Prime Minister’s leadership.”
Mr Raab was sent to the backbenches after Mr Tolley’s report concluded he had engaged in an “abuse or misuse of power” that “undermines or humiliates” while he was foreign secretary. He was also found to have been intimidating to staff by criticising “utterly useless” and “woeful” work while justice secretary.
The senior lawyer led a five-month investigation into eight formal complaints about Mr Raab’s conduct as Brexit secretary and foreign secretary, and in his previous tenure leading the Ministry of Justice.
Though he stopped short of describing the conduct as bullying, Mr Tolley’s findings were consistent with what he said would amount to the offence under the ministerial code.
Mr Raab stayed true to his pledge to step down from cabinet if any bullying claim was upheld.
But the karate black belt went down fighting, criticising the “Kafkaesque saga” and alleging the inquiry had “set a dangerous precedent” by setting a “low” threshold for bullying.
The 49-year-old said he had been warned that “unionised officials” were targeting him, in a widely-criticised tirade that raised concerns about a breakdown of trust between ministers and civil servants.
His departure spells the end of a colourful political career which left him no stranger to controversy, as well as his ambitions of one day taking over in No 10.
Mr Raab, who made an unsuccessful run to replace Theresa May as Tory leader in 2019, was demoted from foreign secretary after accusations of being “missing in action” by being on holiday in Crete during the 2021 Afghanistan evacuation.
