Some have welcomed the move to set a new target to cut emissions to "net zero" by the middle of the century while others gave a more cautious assessment.
Craig Bennett, UK chief executive of Friends of the Earth, said Theresa May's premiership had been "characterised by chronic inaction on climate breakdown" and the 2050 target is "still too slow".
"The next prime minister must legislate to end our contribution to climate breakdown earlier, put carbon-cutting at the centre of policy-making and pull the plug on plans for more roads, runways and fracking," he said.
"It's now time to build the carbon-free future that science requires and the public are so loudly demanding."
Doug Parr, Greenpeace UK's chief scientist, said it was a "big moment", but added there were "questions to be asked about [the] offsetting loophole", which would allow the UK to pay to offset its emissions elsewhere in the world through international carbon credits.
"It is disappointing that the government has ignored its climate advisers' recommendation to exclude carbon offsets - as well as caving into Treasury pressure to review the target in five years' time."
Gareth Redmond King, head of climate change at the environmental charity WWF, said the announcement was a "crucial first step".
"If we want future generations to live on a viable planet where the mass extinctions we're witnessing halt, food security is ensured and coastal regions are safe, then government must accelerate policies and commit resource to slashing emissions, heat our homes with clean energy and make climate action a priority across all departments."
Extinction Rebellion, the protest group that brought parts of London to a standstill with demonstrations in April, said Mrs May's 2050 target was a "death sentence".
"People are already dying and this will only get worse with far off dates," it said.
"Were we to put our minds to it and do what is required to mobilise society to address the threat with the seriousness it deserves, the UK could embrace transformative change and decarbonise in years not decades."
Meanwhile, shadow energy secretary Rebecca Long Bailey raised concerns over how the commitment would be put into practice.
"While this announcement is welcome in theory, in practice it comes from a Conservative government that is off track to meet existing climate targets, that has no plans for legislation or investment needed to cut emissions, and that has dismantled the UK renewable energy sector while pushing fracking," she said.
However, the amendments to the Climate Change Act 2008 were welcomed by Lord Deben, chairman of the government's advisory committee on climate change.
He said: "This step will send a strong signal to other countries to follow suit - and will help to drive the global effort to tackle climate change required by the Paris Agreement."
Dame Carolyn Fairbairn, director-general of business group the CBI, said UK companies were "squarely behind" the commitment and called it the "right response to the global climate crisis".
But she urged the government to ensure the legislation was followed by long-term policies to support decarbonisation across the economy.
"Some sectors will need clear pathways to enable investment in low-carbon technologies, and it is vital that there is cross-government coordination on the policies and regulation needed to deliver a clean future," she said.