Breton, one of the highest-profile members of the European Commission for the past five years, is best known for sparring publicly with tech billionaire Elon Musk and playing a key role in shaping the 27-nation EU's Big Tech regulation, its COVID-vaccine response and efforts to boost defence industries.
A former French minister and industrialist, Breton announced his resignation on X as Commission President Ursula von der Leyen prepares to announce this week who will be part of her new five-year team.
In his resignation letter, Breton alleged that von der Leyen "a few days ago" had asked France to withdraw his name as its pick for the Commission "for personal reasons" in return for an "allegedly more influential portfolio".
He said France would indeed suggest another name in a rare last-minute change.
"In light of these latest developments - further testimony to questionable governance - I have to conclude that I can no longer exercise my duties in the College," Breton said in the letter.
Reuters was unable to immediately verify the allegation. Von der Leyen's office declined to make any immediate comment.
Breton, a former business executive, was the EU's industry and internal market commissioner during her first term.
His and von der Leyen's relationship had taken a turn for the worse over recent months. The French commissioner, a liberal, had angered von der Leyen by publicly criticising her nomination as the European conservative EPP's party candidate to head the Commission for a second term, EU officials have said.
Breton's public feuds with Musk had also been met with dismay among other Commission colleagues, officials added.
KEY JOBS
As the EU's second-biggest member state, France is vying for a major post in the new Commission team, which follows on European Parliament elections in June - the starting point every five years for a shake-up of key jobs in EU institutions that have a major impact on policymaking across the bloc.
Each EU member state will have one seat at the Commission's table, although their political weight and importance varies greatly depending on the portfolio.
Having to replace Breton is likely to add to French President Emmanuel Macron's woes at a time when he is still trying to pull together a government at home with new Prime Minister Michel Barnier.
The French presidency did not immediately reply to a Reuters request for comment.
