BBC NEWS | Climate change: UK to speed up target to cut carbon emissions
The prime minister will say carbon emissions will be cut by 78% by 2035 - almost 15 years earlier than previously planned - which would be a world-leading position.
And for the first time the climate law would be extended to cover international aviation and shipping.
But Labour said the government had to match "rhetoric with reality".
It urged Mr Johnson to treat "the climate emergency as the emergency it is" and show "greater ambition".
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The government has accepted the advice of its independent Climate Change Committee (CCC) to adopt the emissions cut, which is based on 1990 levels.
The move comes as US President Joe Biden prepares to stage a climate summit from Washington.
For households the UK targets will lead to more electric cars, low-carbon heating, renewable electricity and, for many, cutting down on meat and dairy produce.
Homes will need to be much better insulated, and people will be encouraged to drive less and walk and cycle more. Aviation is likely to become more expensive for frequent fliers.
Environmentalists welcomed the government's move, but warned that ministers had consistently failed to achieve previous CCC-set targets.
And they insisted that Chancellor Rishi Sunak must show clearly how the transition is to be funded.
'Not on track'
"This is fantastic - very big news," Leo Murray of the climate charity Possible said.
But he added: "We're not on track to meet previous climate commitments and in many ways the government is still failing."
Mr Murray said ministers were "facing both directions at the same time", as they had scrapped the Green Homes Grant for insulating homes, had not stopped airport expansion and were "still pushing a £27bn roads budget".
Ed Matthew, campaigns director of climate think tank E3G, said: "Setting an ambitious emission reduction target would boost the UK's diplomatic drive to persuade other countries to set out ambitious targets of their own."
He added: "The UK now has the opportunity to spark a global green industrial revolution, but ultimately its credibility will rest on action."
