Nicolas Hulot, France’s ecology minister, Tuesday announced his resignation in a live radio interview.
He told France Inter that he was quitting the government: "I made the decision to leave the government," he said, admitting he felt "all alone in pushing" environmental issues.
The 62-year-old said President Emmanuel Macron and Prime Minister Edouard Philippe were not aware of his decision to leave prior to the announcement, saying "they perhaps would have tried to dissuade me."
"It's a decision of honesty and responsibility," he added, "the most difficult decision of my life."
The France Inter radio hosts did not know he would resign prior to the announcement.
"I don’t want to give the illusion that my presence in government means that we meet the standards on these issues, so I’m taking the decision to leave the government,” said Hulot, to which the presenters replied: "Are you serious?"
Hulot spoke highly of President Emmanuel Macron and Prime Minister Edouard Philippe: "The Prime Minister, the President of the Republic were always affectionate and loyal to me over the last 14 months."
Despite this, the government has not been able to give priority to environmental issues, said the minister, adding that he could only make "small steps".
Government spokesman Benjamin Griveaux appearing on BFM TV Tuesday morning and said: "It's his way of doing things. I think the most basic courtesy would have been to warn the President of the Republic and the Prime Minister."
Hulot was named minister for the first time in May 2017 by Macron, after previously refusing offers from several French leaders.
Having the popular personality in his cabinet was a triumph for Emmanuel Macron, which scored the new leader instant green credentials.
However, 12 months on, environmentalists were starting to question Hulot's role and the government's commitment to the cause.
The environmental activist, a household name in France, formerly presented ecology TV show "Ushuaïa".