Hulot, who became France's best-known environmentalist as the face of the Ushuaia TV programme, told France Inter radio on Tuesday: "I've taken the decision to leave the government". But he had not informed Macron of his decision beforehand.
"This decision has been formed throughout the summer," said Hulot adding that he felt "all alone" on environmental issues within the cabinet.
Hulot, one of the most respected members of the cabinet among the French public, said he had "huge admiration" for Emmanuel Macron but said they differed on the subjects that mattered to him and he lamented the lack of change the government has brought about.
"Have we starting to reduce the use of pesticides?" The answer is no. Have we started to stop the erosion of biodiversity, the answer is no," said Hulot.
"We're taking little steps, and France is doing a lot more than other countries, but are little steps enough?... the answer is no," he added.
The now ex-minister was known to be aggrieved by Macron's plan to reform hunting laws to make it easier for hunters to gain licences, but Hulot said his resignation was down to a number of reasons.
"My decision does not come only from a divergence on the hunting reform, it's an accumulation of disappointments... I don't have faith in the state anymore," he said.
"I don't want to lie anymore," said Hulot. "I don't want to give the illusion that my presence in the government means we are up to the task of meeting these [environmental] challenges".
Hulot said he not informed Macon nor Prime Minister Edouard Philippe of his decision to step down before announcing it on French radio, prompting a rebuke from government spokesman Benjamin Griveaux, who blasted "a lack of courtesy".
When Hulot joined the President Emmanuel Macron's government in May last year, he made it clear he was unsure whether he would have much of an impact.
He had hesitated about joining the ministerial team, having refused similar offers from previous French leaders.
"The urgency of the situation requires me to try everything to help a new societal model emerge," he said in a statement after finally committing.
For Macron, recruiting Hulot was a political coup, giving the new centrist leader instant environmental credentials after an election campaign focused on economic growth.
But 12 months later, many campaigners began to believe that Hulot, the minister of environmental transition, amounted to little more than political "greenwashing" -- eco-friendly cover for a government that is not really committed to the cause.
A succession of French government decisions have come under fire from environmentalists, fuelling reports that Hulot was chafing at being accused of "retreats" from his agenda and getting ready to throw in the towel.
Yet in June he signalled that he would stay on.
"Every day we make compromises, because we're not living in a fairy tale," Hulot said on French radio at the time.
"I'm here for the middle and the long term."
Departure a blow for Macron
Hulot's resignation will be a major blow for Macron, who has positioned himself as a global leader committed to tackling global warming as he seeks to compensate for US President Donald Trump's policy of climate change denial.
In December, Macron hosted 50 world leaders at the "One Planet Summit", talking of jump-starting the transition to a greener economy two years after the historic Paris agreement to limit climate change.
Having declared "Make our planet great again" after Trump pulled out of the Paris accord last year, Macron followed up with a new catchphrase in front of the US Congress in April.
"There is no Planet B," he told American lawmakers.
But behind the international grandstanding, critics point to a series of disappointments in France, where Hulot lost out and powerful farming and industrial lobbies are seen by some to have prevailed.
Last December, France backed a new EU plan to combat endocrine disruptors -- chemicals which can cause tumours, birth defects and other hormonal disorders -- which was criticised as too weak by many scientists and NGOs.
Environmentalists had battled for a much stricter definition to help limit the dangers from disruptors such as PCBs and pesticides found in food, make-up, toys, paint and many other household items.
Macron had also promised that Paris would ban the widely used but controversial pesticide glyphosate within three years after the EU renewed its licence last November.
But in the end, the government has left it to industry bodies to self-regulate and phase out the chemical, produced by US agro-industrial giant Monsanto, by 2021.
These examples highlight "the gap between what (the president) says and what he does," noted political scientist Simon Persico in a highly critical column in Le Monde newspaper earlier this year.
"Emmanuel Macron can declare 'Make the planet great again', but such publicity-seeking statements are not followed by any proper reform," Persico wrote.