Ms Truss was on Tuesday sworn in as prime minister of Britain when she met with Queen Elizabeth II at Balmoral in Scotland, a day after she was declared the winner of the Tory leadership contest, beating her rival Rishi Sunak.
The Tory hardliner secured 81,326 votes from Conservative Party members, while Mr Sunak received 60,399 votes.
Ms Truss travelled to Aberdeenshire early on Tuesday where the monarch, 96, asked her to form a new government.
Who is Kwasi Kwarteng?
Born in east London to a barrister mother and economist father who emigrated from Ghana, Mr Kwarteng was an only child.
He attended the famed Eton College in Berkshire, the elite school known for churning out Conservative MPs and prime ministers such as Mr Johnson and David Cameron.
Going on to read classics and history at the University of Cambridge, he graduated with a first in both, before heading across the Atlantic to study at Harvard in the US. Upon his return to the UK, he earned a doctorate in economic history from Cambridge.
Mr Kwarteng worked as a financial analyst at investment banks including JP Morgan Chase and wrote a book titled Ghosts of Empire about the legacy of the British Empire before venturing into politics.
He was elected as MP for Spelthorne in Surrey in 2010 and campaigned for Brexit in the run-up to the 2016 EU referendum.
The MP was regarded as a rising star within the Tory party and in 2017 was appointed parliamentary private secretary to the chancellor at the time, Philip Hammond.
The following year, he was made Brexit secretary and in 2019 supported Mr Johnson in the Conservative leadership race.
When Mr Johnson entered No. 10, he rewarded Mr Kwarteng for his loyalty by making him an energy minister.
In 2021, Mr Kwarteng was promoted to business secretary, making him the first black secretary of state.
Commitment to 'lean state'
Amid rising speculation that Ms Truss has favoured Mr Kwarteng for the job, he used an op-ed in The Financial Times to say the next government will behave in a “fiscally responsible” way.
He attempted to back up Ms Truss’s tax-cutting strategy, which her rival Mr Sunak warned would exacerbate Britain’s economic woes.
Mr Kwarteng said there would be “some fiscal loosening” in a Truss administration to help households through the winter, stressing that it is the “right thing” to do.
He said the UK does not need “excessive fiscal tightening”, pointing to the country’s ratio of debt to gross domestic product compared with other major economies.
“The OECD [Organisation for Economic Co-operation and Development] has said that the current government policy is contractionary, which will only send us into a negative spiral when the aim should be to do the opposite,” Mr Kwarteng wrote.
“But I want to provide reassurance that this will be done in a fiscally responsible way.
“Liz is committed to a lean state and, as the immediate shock subsides, we will work to reduce the debt-to-GDP ratio over time.”
Mr Kwarteng offered a vision for how he would operate the Treasury, as he said the next administration would be “decisive and do things differently”.
“That means focusing on how we unlock investment and growth, rather than how we tax and spend. It is about growing the size of the UK economy, not burying our heads in a redistributive fight over what is left,” he said.
His comments directly echoed those of Ms Truss on Sunday when she insisted that her plan to reverse the rise in national insurance is “fair”, despite it directly benefiting higher earners.
She told the BBC “growing the economy benefits everybody” and it is “wrong” to look at everything through the “lens of redistribution”.
Rejection of 'identity politics'
In an article for trueafrica.co in 2016, Mr Kwarteng explained why he bridles at the idea he should be expected to speak out about “black” issues.
He said MPs from ethnic minorities were expected to constantly “engage with ‘black’ issues, like knife crime in London”, while ignoring the positives about such communities.
Mr Kwarteng expressed disappointment that “the incredible appetite for entrepreneurship found among parts of the African community in Britain” was less talked about.
“It’s as if being from a particular background gives a politician a God-given right to speak on behalf of every single person from that background,” he wrote.
“This is the heart of identity politics, which has dominated the left for a couple of decades.”