George Osborne's announcement came via the Russian-owned "Evening Standard" newspaper where he has been appointed editor. A leading EU remain campaigner, he was fired as finance minister when May took over.
Along with his school friend David Cameron, Osborne had led the 2016 campaign in favor of Britain remaining in the European Union.
His decision to withdraw from politics, for now, was announced via the social media site of the Evening Standard as "Breaking News: George Osborne quits as MP."
"I am stepping down from the House of Commons, for now," Osborne wrote in his resignation letter, the Evening Standard reported on Wednesday. "I will remain active in the debate about our country's future and on the issues I care about.”
Russian Evgeny Lebedev and his father, the former Soviet spy Alexander, bought a 65 percent share in the Evening Standard in 2009. Lebedev the younger announced Osborne's appointment earlier this year: "I am proud to have an editor of such substance, who reinforces The Standard's standing and influence in London and whose political viewpoint - socially liberal and economically pragmatic - closely matches that of many of our readers."
In a letter to his constituents in Tatton, Cheshire - posted later on Twitter - Osborne wrote "I want new challenges. I'm very excited about the opportunity to edit the Evening Standard."
A constituency with an end
The parliamentary seat of Tatton, in the northwest of England, is due to be abolished in boundary changes which were scheduled to come into effect in 2018.
The former Chancellor of the Exchequer has no formal journalistic experience, and there were suggestions he could face potential conflicts of interest editing the Evening Standard while he remained a Member of Parliament.
Although he failed to get a place on a trainee scheme for The Times newspaper in 1993 Osborne became a freelance political columnist before being appointed head of the Conservative Party Research Department's political section. He first stood for Tatton in 2001 and became shadow chancellor in 2005, graduating to the full role when the Conservatives won the largest number of votes in the 2010 elections and formed a coalition with the Liberal Democrats. After the Conservative election win in 2015, Osborne was sacked by current premier Theresa May when she took over from Prime Minister David Cameron, who resigned following the Brexit vote.
'The spy who came in for the gold'
Osborne is also reported to be earning 650,000 pounds ($833,000, 770,000 euros) per year from investment house BlackRock where he works four days each month. While an MP he has also enjoyed roles with the Washington Speaker's Bureau as a speaker, as Chairman of the Northern Powerhouse Partnership and as a Fellow of the McCain Institute.
The Lebedevs also own the "Independent" newspaper and television channel "London Live." Father Alexander worked for the Russian secret service, the KGB, before becoming a banker and gaining the nickname "the spy who came in for the gold."
The 37-year-old Lebedev went to school in London and became a British citizen in 2010. He told the "Guardian" newspaper in 2012 that as a child, he wanted to be a cosmonaut "like all good Soviet children."
Labour MPs not standing
Three opposition Labour MPs have also announced they will not stand again in the June poll: Iain Wright of Harlepool said "I would like to do other things and now is a good opportunity to do so."
Tom Blenkinsop, MP for Middlesbrough South and East Cleveland, said his differences with party leader Jeremy Corbyn prevented him from standing again: "I have made no secret about my significant and irreconcilable differences with the current Labour leadership."
Alan Johnson, the MP for Hull West and Hessle, indicated his retirement was due to age: "For me the personal decision is whether to retire now or in 2022 when I'll be into my 70s," he said, adding "I've decided that going now will give me the opportunity to do other things with my life."
jm/msh (AP, AFP, Reuters)