The former Prime Ministers signed an amendment to the Government Equalization Act brought by Simon Clarkewho served as a minister in both their governments, to allow wind turbine development on land.
Clarke said he was “delighted” to have their support.
It marks the couple’s first major parliamentary intervention since leaving Downing Street.
Ms Truss moved to relax planning rules during her short tenure at No 10, but Mr Johnson did not seek to overturn the effective moratorium on onshore wind in place since 2015, when he was in office.
Sir. Sunak has already faced a significant challenge on planning policy from his own party.
The Prime Minister pulled a vote, scheduled for Monday, on legislation that would set a target of building 300,000 homes a year after about 50 Tory Members of Parliament threatened to revolt.
Sir. Clarke, a former level-up secretary, tweeted: “Delighted to have the support of @BorisJohnson and @trussliz, along with MPs from across the Conservative Party, for my amendment to allow onshore wind where (and only where ) there is collective consent.
“A pro-growth, pro-green policy at a time when we need both.”
Calls to end the ban on new onshore wind farms have grown in line with efforts to secure Britain’s energy independence, as Russia’s invasion of Ukraine has squeezed supplies.
Sir Keir Starmer has promised that a Labor government would lift the planning ban as part of its plan to make Britain a clean energy superpower.
The Labor leader has described Mr Sunak’s refusal to do so as a “national act of self-harm, stifling our economic potential”.