The UK's social safety net has been "deliberately removed and replaced with a harsh and uncaring ethos", a report commissioned by the UN has said.
Special rapporteur on extreme poverty Philip Alston said "ideological" cuts to public services since 2010 have led to "tragic consequences".
The report comes after Prof Alston visited UK towns and cities and made preliminary findings last November.
The government said his final report was "barely believable".
The £95bn spent on welfare and the maintenance of the state pension showed the government took tackling poverty "extremely seriously", a spokesman for the Department for Work and Pensions (DWP) said.
Prof Alston is an independent expert in human rights law and was appointed to the unpaid role by the UN Human Rights Council in June 2014. He spent nearly two weeks travelling in Britain and Northern Ireland and received more than 300 written submissions for his report.
He concluded: "The bottom line is that much of the glue that has held British society together since the Second World War has been deliberately removed and replaced with a harsh and uncaring ethos."
The Australian professor, who is based at New York University, said government policies had led to the "systematic immiseration [economic impoverishment]" of a significant part of the UK population, meaning they had continually put people further into poverty.
Some observers might conclude that the DWP had been tasked with "designing a digital and sanitised version of the 19th Century workhouse, made infamous by Charles Dickens", he said.
The report cites independent experts saying that 14 million people in the UK - a fifth of the population - live in poverty, according to a new measure that takes into account costs such as housing and childcare.
In 2017, 1.5 million people experienced destitution, meaning they had less than £10 a day after housing costs, or they had to go without at least two essentials such as shelter, food, heat, light, clothing or toiletries during a one-month period.
Despite official denials, Prof Alston said he had heard accounts of people choosing between heating their homes or eating, children turning up to school with empty stomachs, increased homelessness and food bank use, and "story after story" of people who had considered or attempted suicide.
He said the cause was the government's "ideological" decision to dismantle the social safety net and focus on work as the solution to poverty.
"UK standards of well-being have descended precipitately in a remarkably short period of time, as a result of deliberate policy choices made when many other options were available," said Prof Alston.
Analysis: 'Life has become a lot harder'
By Michael Buchanan, BBC social affairs correspondent
To anyone familiar with the shifting landscape of Britain's poorest communities since 2010, there is nothing factually new in these findings.
By highlighting them in one short, 20-page report, however, Philip Alston raises a fundamental question - is the government, and the country, comfortable with the society that we've become?
He outlines the normalisation of food banks, rising levels of homelessness and child poverty, steep cuts to benefits and policing, and severe restrictions on legal aid.
In Professor Alston's view, these are the unequivocal consequences of deliberate, calculated political decisions.
Ministers have long argued they had no choice but to cut public spending. Whatever the motivation, life has become a lot harder in recent years for millions of people in the UK.
The DWP said that the UN's own data put the UK 15th on the list of the happiest places to live.
"This is a barely believable documentation of Britain, based on a tiny period of time spent here. It paints a completely inaccurate picture of our approach to tackling poverty," a spokesman said.
"All the evidence shows that full-time work is the best way to boost your income and quality of life," the spokesman added.
Prof Alston praised the "resilience, strength and generosity" of British people, as well as the compassion of local officials and volunteers.
And he said there had been some positive developments, with increases in the Universal Credit work allowances expected to lift 200,000 people out of poverty, and plans to introduce a consistent measure of poverty.
But he said the "massive disinvestment" in the social safety net continued, making the changes seem like "window dressing to minimise political fall-out".
Despite the government's focus on work and record levels of employment, about 60% of people in poverty are in families where someone works, Prof Alston said.
He said this, along with welfare cuts, created a "highly combustible situation that will have dire consequences" in an extended economic downturn.