By a 230 to 197 vote in the Democratic-majority House, the 45th US president becomes just the third occupant of the White House in American history to be impeached.
Democrats said they had "no choice" but to formally charge the Republican president, whose impeachment along stark party lines places an indelible stain on his record while driving a spike ever deeper into the US political divide. "What is at risk here is the very idea of America," said Adam Schiff, the lawmaker who headed the impeachment inquiry, ahead of the vote.
Trump will now stand trial in the Senate, where his Republicans hold a solid majority and are expected to exonerate him.
The House vote came four months after a whistleblower blew open the scandal of Trump pressuring Ukraine's president to investigate his potential White House challenger in 2020, the veteran Democrat Joe Biden.
After a marathon of 10 hours of debate, lawmakers were to vote quickly on the second article of impeachment facing Trump — for obstructing the congressional probe into his Ukraine dealings by blocking the testimony of subpoenaed White House aides.
Despite testimony from 17 officials that Trump leveraged his office for domestic politic gain, the president maintained his innocence throughout the impeachment inquiry — furiously denouncing it as a "witch hunt," an "attempted coup" and on Wednesday as an "assault on America."
Trump spent the first part of the day holed up at the White House, sending out tweets reflecting his frustration, anger and predictions of revenge in the 2020 election. But as the vote took place, the 73-year-old was on friendlier territory.
In an extraordinary split screen moment, while the House was casting votes to impeach him, thousands of Trump's most fervent supporters were cheering him at a rally in Michigan where he railed against a "radical left" he said was "consumed with hatred."
Democrats are "trying to nullify the ballots of tens of millions of patriotic Americans," he charged. "Four more years, four more years," the crowd chanted back.
Trump railed against a Democratic Party "consumed with hatred" after the impeachment. "While we're creating jobs and fighting for Michigan, the radical Left in Congress is consumed with envy and hatred and rage, you see what's going on," the Republican leader seethed at campaign rally in the state. "These people are crazy."
Trump said the Democratic Party, which controls the House of Representatives where the votes took place, was "trying to nullify the ballots of tens of millions of patriotic Americans."
'Threat to national security'
Neither of the two previous presidents impeached since 1789, Andrew Johnson in 1868 and Bill Clinton in 1998, was convicted in the Senate, and both held onto their jobs.
But despite the high likelihood of Trump being cleared by Senate Republicans, Democrats said the evidence against him was overwhelming and forced them to act.
"It is tragic that the president's reckless actions make impeachment necessary. He gave us no choice," said House Speaker Nancy Pelosi. "It is a matter of fact that the president is an ongoing threat to our national security and the integrity of our elections."
Both camps approached the vote with solemnity. "It's a big responsibility, it's sobering, and I think the members feel that way too," House Democrat Diana DeGette told AFP.
"I come to this floor not as a Republican, not as a Democrat, but as an American," said independent legislator Justin Amash. "Impeachment is about maintaining the integrity of the office of the presidency."
'Triggered into impeaching'
The day of dramatic and often angry oratory saw both sides delving deep into Constitutional law, citing the intentions of the country's hallowed founders such as Benjamin Franklin or Alexander Hamilton.
Republicans repeatedly drove the line that the Democrats rushed the investigation; Trump was treated more unfairly than witches put on trial in the 17th century Americas — or even than Jesus Christ, they claimed.
"Pontius Pilate gave Jesus the opportunity to face his accusers. During that sham trial, Pontius Pilate afforded more rights to Jesus than the Democrats afforded this president and this process," said Georgia Republican Barry Loudermilk.
They accused Democrats of being driven by a party fringe of socialist extremists and "Trump-haters," and warned that impeaching Trump would backlash against the party in national elections next November.
"This is not about the Ukraine, it's about power," said Republican Matt Gaetz. "Voters will never forget that Democrats have been triggered into impeaching the president, because they don't like him, and they don't like us."
Democrats countered that Republicans were not addressing the charges and evidence, instead issuing blanket denials and counter-accusations. "We do not hear, because we cannot hear, because they cannot articulate, a real defence of the president's actions," said Jerry Nadler, whose Judiciary Committee drafted the charges against Trump.