Brett Kavanaugh, who faced multiple allegations of sexual misconduct, has been sworn in as a justice of the Supreme Court after the closest Senate vote in more than 100 years.
Judge Kavanaugh was voted in by 50 votes to 48, handing Donald Trump a huge victory ahead of the midterms in November.
At a rally in Topeka, Kansas, moments after Judge Kavanaugh took up his new role, President Trump praised him as a "loving husband, devoted father, and faithful public servant", thanking Republicans for not backing down to the "radical Democrats".
He said: "I stand before you today on the heels of a tremendous victory for our nation."
He added that what the Kavanaugh family had "endured" was "unthinkable", and called it a "shameless campaign of political and personal destruction".
While Judge Kavanaugh was sworn in, in a private ceremony, protests continued outside, with some even rushing to the doors and banging on them in fury.
A public swearing-in ceremony will take place on Monday evening in the White House's East Room.
Senators debated the decision before casting their vote, watched on by many in the public gallery.
Senate leader Mitch McConnell said: "The court guards our right and the Senate guards the court. Members of this body are duty bound to make sure men and women of the highest distinction are appointed to the Supreme Court – fortunately that is the case with the one that stands before us today.
"For 12 years he has excelled on the bench. Yet, we have studied the result of seven FBI inquiries – which have found no evidence of misconduct. He will make the Senate and the country proud. He unquestionably deserves confirmation."
Democratic Senator Chuck Schumer said: "Republicans knew he was very flawed, but once he was nominated, it became a steam roller. They were intent on shrouding the truth because they knew that if the truth came to light, he would be exposed as a flawed individual."
Mr Trump's choice of Judge Kavanaugh to replace Anthony Kennedy on the Supreme Court was controversial from the beginning, but initial concerns were based around his conservative views.
Protests began in earnest when Dr Christine Blasey Ford came forward, alleging he had assaulted her at a party in the 1980s.
Her hearing sparked a supplemental FBI probe into his background, which created a week long delay of the vote. He emphatically denied the allegations.
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But the report from the FBI was met with mixed response, with survivors and Democrats saying it was "insufficient", but Mr Trump and Republicans calling it "thorough" and "professional".
Judge Kavanaugh will be able to start work quickly, with his attention first turned to arguments at the court on Tuesday on two cases involving prison sentences for repeat offenders.