The promise, which involves amending soon-to-be approved legislation that requires Britain to cut carbon emissions by 60 percent on 1990 levels by 2050, came after a recommendation to do so from a government-appointed committee.
"We will amend the Climate Change Bill to cut greenhouse gas emissions by 80 percent by 2050, and that target will be binding in law," Energy and Climate Change Secretary Ed Miliband said, in a statement to the House of Commons.
The cuts will cover all industries - including shipping and aviation - and, according to the chair of the committee that made the initial recommendations, would cost around one to two percent of gross domestic product (GDP) in 2050 and was "challenging but feasible."
Miliband said other laws would be amended to encourage small-scale energy generation through the use of home-based wind turbines or solar panels.
He also called on European countries - which have considered rolling back previous commitments to combat climate change in recent days amid the global financial crisis - to follow suit.
Campaigners welcomed the carbon-cutting pledge, but cautioned that Britain should ensure it lowered carbon emissions locally, and did not rely on the use of carbon offsetting, whereby individuals or companies can pay for green projects elsewhere to "offset" their own emissions.
Describing it as "a great step forward," WWF-UK chief executive David Nussbaum warned: "The key issue now is to ensure that we move swiftly to a low-carbon economy which creates new jobs here in the UK ... rather than relying excessively on imported carbon credits."
Britain became the first country in the world to introduce legally-binding cuts in emissions of carbon dioxide, the gas seen as largely to blame for climate change, when the Climate Change Bill completed its passage through both houses of parliament in March.
It is now awaiting Royal Assent, effectively a rubber stamp that shows the monarch has approved it.