Mr Trump emphasised the size of the tax cuts during the bill signing, calling the legislation "a bill for the middle class and a bill for jobs".
But Democrats, such as House Minority Leader Nancy Pelosi, have branded the bill a "monumental con job" that will benefit the rich at the expense of America's poorest.
The legislation gives generous tax cuts to corporations – “That's probably the biggest factor in our plan," Mr Trump admitted earlier this week – while giving the majority of Americans a more modest tax break that will expire in 2025. The bill also eliminates the corporate alternative minimum tax and raises the threshold for the estate tax, which affects property passed down when a family member dies.
"With every iteration, the GOP tax scam becomes even more cowardly, outrageous, dishonest, brazen-theft from middle class families, giving money from them to the richest people in our country and to corporations," Ms Pelosi said earlier this week.
Perhaps most concerningly for Democrats, the legislation repeals Obamacare's individual insurance mandate. The mandate requires all Americans to either obtain health insurance or pay a fee, in a bid to keep premiums low. Experts say repealing the mandate could increase premiums by up to 10 per cent, and leave 13m more Americans without health insurance by 2027.
Repeating comments from earlier this week, Mr Trump told reporters at the bill signing that "Obamacare is over," adding: "We have essentially repealed Obamacare."
Obamacare has not been repealed, and Americans were still able to sign up for individual health insurance plans for 2018 through the government-run exchanges. Nearly 9m people signed up through the exchanges this winter – nearly the same amount as last year, despite the shorter registration period imposed by the Trump administration.
The tax bill's passage is the first major legislative victory for the Trump administration and a welcome win for Republicans in Congress, who failed numerous times to repeal Obamacare this summer.
Republicans claim that the tax cuts will embolden businesses to expand and promote economic growth. Signing the bill on Friday, Mr Trump claimed corporations were "literally going wild" over the legislation.
The bill will also raise the federal deficit, however – a prospect that concerned Democrats and Republicans alike. House Speaker Paul Ryan admitted earlier this week that "nobody knows" if economic growth spurred by the tax breaks will make up for the reduction in tax revenue.
But Republicans pushed the bill through the House and the Senate in a party-line vote, getting it to the President's desk in time for him to sign in it before jetting off to Mar-a-lago for the holidays.
“We did a rushed job today,” Mr. Trump said at the bill signing. “It’s not fancy, but it’s the Oval Office. It’s the great Oval Office.”
Join our new commenting forum
Join thought-provoking conversations, follow other Independent readers and see their replies