He heralded the "beginning of a new era" for the economy, dominated by tax cuts, funded through government borrowing, and deregulation in pursuit of growth.
Paul Johnson, from the Institute for Fiscal Studies (IFS), called the chancellor’s announcement the "biggest tax-cutting event since 1972".
The Treasury estimates that the tax cuts will cost nearly £45bn a year in 2026, and the total package would be funded by increasing borrowing by £72.4bn.
To cover the costs, the measures would have to drive up gross domestic product (GDP) by 1% on current forecasts every year for five years, the Treasury estimated.
Here's when the biggest tax cuts in 50 years kick in, and what the new rates will be.
Kwarteng said that measures to cut income tax and additional tax rebate will simplify the tax system and make the UK more competitive.
From April 2023, the basic rate of income tax will be cut to 19p in the pound, down from 20p.
That means 31 million people will be better off by an average of £170 per year, the chancellor said.
Additionally, the government will abolish the 45% additional tax rate, in its place there will be a single higher rate of income tax of 40%.
Cutting the top rate of income tax will save the top earners, on average around £10,000 a year, according to Treasury estimates.
But Torsten Bell, chief executive of the Resolution Foundation think tank, said those earning £1m annually will get a £55,000 tax cut next year.
The recent 1.25% increase in national insurance (NICs) will be reversed from 6 November. The chancellor said this delivers a tax cut for 28 million people worth on average £330 every year.
Some 920,000 businesses are set to save nearly £10,000 on average next year thanks to the change.
The government also cancelled the planned tax hike to fund health and social care.
Kwarteng said that the extra funding for the NHS and social care services will be maintained at the same level.
The net cost of reversing Boris Johnson and Rishi Sunak’s 1.25 percentage point increase to NICs imposed in April was put at around £15bn per year.
A planned hike in corporation tax was also cancelled on Friday, meaning the levy won't rise to 25%, but instead remain at 19%.
The chancellor says this is the lowest rate in the G20 and will return about £19bn a year to the economy.
"That’s £19bn for businesses to reinvest, create jobs, raise wages, or pay the dividends that support our pensions," he said.
The chancellor said he would introduce VAT-free shopping for overseas visitors, although when this will be brought in is yet to be announced.
Stamp duty land tax will be cut from "today" [Friday 23 September], Kwarteng said.
That means that no levy will be paid for the first £250,000 of a property's value — double the £125,000 allowed currently.
The threshold for first-time buyers rose from £300,000 to £425,000. The value of the property on which first-time buyers can claim relief is lifted from £500,000 to £625,000.