They include the most diverse top team in British history ever: Kwasi Kwarteng as Chancellor of the Exchequer, James Cleverly as foreign secretary and Suella Braverman as interior minister.
They face a daunting in-tray of issues, most notably decades-high inflation and how to deal with energy bills set to rise by 80 percent next month and then  again in January.
Meanwhile, the Bank of England has tipped the country to fall into recession later this year.
She must also navigate the combustible issue of post-Brexit trading arrangements in Northern Ireland, and in one of her first calls with a foreign leader late Tuesday, she agreed with US President Joe Biden “on the importance of protecting” peace in the province.
In its readout of the call, the White House also said Truss and Biden addressed “the challenges posed by China (and) preventing Iran from ever acquiring a nuclear weapon.”
But Truss was bullish as she entered Downing Street for the first time as premier, narrowly avoiding a heavy downpour.
“I am confident that together we can ride out the storm,” she said.
Her new ministers may be asked to sign off immediately on a plan to freeze energy bills for the coming winter, possibly longer, a measure that would cost tens of billions of pounds, according to reports.
Tax cuts and diverting some health funding to social care could also reportedly be on the agenda.
“I will cut taxes to reward hard work and boost business-led growth and investment,” Truss promised, while also vowing “action this week” on gas and electricity bills and broader energy policy.
‘Almost ungovernable’
After Cabinet, Truss will travel to the House of Commons to spar with opposition Labor leader Keir Starmer, in the rival pair’s first Prime Minister’s Questions session.
The often rowdy weekly session, which sees the prime minister quizzed by MPs, will test Truss’s political mettle and rhetorical skills as well as her level of Conservative support.
The 47-year-old won an internal ballot of Tory members on Monday, securing 57 percent of the vote, after a grueling contest against former finance minister Rishi Sunak that began in July.
But the initial stage of the contest saw her net the support of less than a third of the parliamentary party.
She now faces a tough challenge reuniting the ruling Tories following a bitter leadership battle.
Conservative MPs are “almost ungovernable” and have “no appetite to cope with difficult decisions,” according to a government insider quoted by the Financial Times on Monday.
“They did for Boris and they may do for Liz, too,” the source told the paper.
Truss will likely face a volley of hostile questions from Starmer and the Labor ranks, as they look to capitalize on months of Tory disarray.
Labor has opened up a double-digit lead in the polls but may have to wait two years for the next general election.
Truss vowed Monday to lead the Conservatives to victory “in 2024”, with an election due by January 2025 at the latest.
‘Dreadful policy’Â
Truss, who pitched herself to the Tory grassroots as a tax-cutting free-trade champion ready to slash taxes immediately to turbo-charge growth, faces warnings that these moves could make inflation worse.
The UK has already seen prices rise this year at their steepest rate for four decades, driven by spiraling energy costs.
Under her mooted plans to tackle the situation, gas and electricity bills for both households and businesses would be capped near current levels for the coming winter at least.
The government would lend or guarantee private sector loans to energy providers to make up the difference they pay with soaring global wholesale prices.
It remains unclear whether the government will pay for the plan through extra borrowing or ask consumers to pick up the tab over the next two decades through levies on their energy bills.
Paul Johnson, of the respected Institute for Fiscal Studies (IFS) think-tank, said it was “a dreadful policy” but likely necessary.
“Hugely expensive, untargeted, increases risk of shortages,” he noted on Twitter.
But he warned the scale of the problem “means there may just be no practical alternative.”