Theresa May's promise is one of her final announcements as prime minister.
Big changes like us eating less meat, switching to green electricity, and trees being planted to soak up carbon dioxide would be necessary to achieve zero emissions by 2050.
The Rt Rev Nicholas Holtam, Bishop of Salisbury said: "This announcement is very welcome, and the UK can be proud to be setting an example by making this commitment to address the global climate emergency.
"But commitment alone is meaningless unless it is backed up by relentless action, which must remain our priority in the coming decades.
"Christians and people of all faiths have long called for action on climate change both to preserve the natural world on which we all rely, and to protect God's creation for generations to come.
"Climate change affects us all, but the world's poorest are most vulnerable to extreme weather events and the least able to cope with the impact."
The new pledge has also been met with criticism, with some groups saying the target should be met sooner.
Paul Cook, Tearfund's Head of Advocacy told Premier while he welcomes the pledge, more could be achieved sooner.
Speaking on Premier News Hour, he said: "That sets a really important precedent that we now want other countries to follow as well.
"Ideally we would like that to be sooner. They said 2050, we think its possible to achieve much sooner than that.
"Nevertheless, this is a really important day and we want to take this victory and really continue to push and hold governments to account."
Scotland has already committed to reducing greenhouse gas emissions to net-zero by 2045, five years ahead of the UK government's target.
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