Gorsuch, 49, took the Constitutional Oath in a private ceremony, administered by Chief Justice John Roberts in the Supreme Court's Justice's Conference Room. He was accompanied by his wife Louise, who held the Bible, and his two daughters.
Later, in a public ceremony at the White House, Justice Anthony Kennedy -- Gorsuch's former boss -- administered the Judicial Oath.
Confirmed by the Senate on Friday after a bitter months-long fight, Gorsuch was sworn in as the US Supreme Court's ninth justice.
He fills up the seat that became vacant by the death of Justice Scalia last year.
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With this Judge Gorsuch became the 113th Supreme Court judge and the first one to be confirmed by the Senate and sworn in under the 45th US President Trump.
"I have no doubt you will rise to the occasion, and the decisions you make will protect our Constitution today and for many generations of Americans to come," he said.
Gorsuch has been compared favourably to Scalia by conservatives hopeful for another originalist on the court.
The high stakes led Republicans to trigger the "nuclear option" last week to kill the 60-vote filibuster threshold for Supreme Court nominees.