WASHINGTON — Colorado appeals court judge Neil M. Gorsuch took his oaths to be the Supreme Court’s 113th justice Monday, first in a private ceremony at the court and later at a Rose Garden ceremony with the man who nominated him, President Donald Trump.

At the first, private event in a grand room inside the Supreme Court, Chief Justice John G. Roberts Jr. administered the oath that all federal employees take. All eight justices and most of their spouses were on hand, as well as Maureen Scalia and Eugene Scalia, the widow and son of the justice Gorsuch is replacing, Antonin Scalia.

Gorsuch’s wife, Louise, held a family Bible, and his daughters Emma and Belinda looked on.

On a sunny spring day at the White House Rose Garden, Justice Anthony M. Kennedy, for whom the 49-year-old Gorsuch once served as a clerk, led him through a second oath that justices take to impartially interpret the laws “and do equal right to the poor and to the rich.”

It was the conclusion of a nearly 14-month process to fill Scalia’s seat, with Republicans winning a bitter battle to ensure his replacement was a like-minded disciple who will restore a conservative majority on the court for years to come.

A Marine Corps string quartet played softly in the Rose Garden as the Trump West Wing poured in to watch history.

“It’s a privilege to have you here to join in this historic moment on this very beautiful spring day,” Trump said, introducing his pick to the high court. “Spring is really the perfect backdrop for this joyful gathering of friends because together we are in a process of reviewing and renewing and also rebuilding our country.”

Trump, whose young White House has been roiled with turmoil and infighting, seemed eager to celebrate Gorsuch’s appointment — one of his first clear victories, and one of particular importance to his base and the Republican establishment generally.

“I’ve always heard that the most important thing that a president of the United States does is appoint people, hopefully great people like this appointment, to the United States Supreme Court, and I can say this is a great honor,” the president said, before straying from his teleprompter remarks and ad-libbing a bit of praise for himself.

“And I got it done in the first 100 days,” he said, to laughter. “You think that’s easy?”

Both Trump and Gorsuch, in their remarks, noted the historical nature of Kennedy swearing in his former law clerk. “That’s sort of a big deal, isn’t it?” the president said. “That’s sort of good.”

Gorsuch spoke of the pride he felt taking the oath from his early boss. “I cannot tell you how honored I am to have here today my mentor, Justice Kennedy, to administer the judicial oath, a beautiful oath, as he did for me 11 years ago when I became a circuit judge,” Gorsuch said.

In brief remarks that were largely devoted to thanking others, Gorsuch thanked the team that helped usher him through the Senate confirmation process (“for their humor, for their sage advice, for their faith”), both his “dear friends” and former law clerks (“you know your names are etched in my heart forever”), and the Scalia family (“I will never forget that the seat I inherit today is that of a very, very great man”).

Gorsuch was confirmed by a 54-45 vote Friday, the closest margin since Justice Clarence Thomas was approved more than 25 years ago. The Republican-controlled Senate did away with the filibuster for Supreme Court nominees to confirm Gorsuch. Democrats said they consider the seat “stolen,” because Republicans refused to act on President Barack Obama’s nominee for the court, Judge Merrick Garland.

Gorsuch will be put to work immediately. The court meets privately Thursday to consider cases for next term. On the list is a plea that the court decide whether the Second Amendment grants a right to carry firearms outside the home. Another asks whether businesses may refuse to provide wedding services to same-sex couples.

Next week, the court begins its last round of oral arguments for the term. Gorsuch, who in the past has defended the rights of religious objectors to laws they say violate their beliefs, could be the deciding vote in a major separation of church and state case from Missouri.

And it is possible the court may reveal that it is deadlocked on several cases it already has heard this term. The court, with four liberals nominated by Democratic presidents and four mostly conservative justices picked by Republicans, would schedule rehearings in those cases so Gorsuch could break the tie.

And in a matter of weeks, the court might be called upon to get involved in Trump’s second travel ban targeting refugees and those entering the U.S. from certain countries.

In some ways, Gorsuch is the prototypical justice. He is the 109th man to hold office among the 113 justices in the court’s history. All but two of the men were white. He is a favorite of the conservative legal establishment and has family roots in Republican politics.

Like five of his colleagues, Gorsuch attended Harvard Law School — the others went to Yale. He was hired as a Supreme Court clerk by fellow Coloradan Justice Byron White. Because White had retired by then, Gorsuch was loaned to Kennedy for the 1993-94 term.

He becomes the first former clerk to serve on the court alongside his boss.

Gorsuch is different in other ways. Coming from the U.S. Court of Appeals for the 10th Circuit, he is the court’s only Westerner. Kennedy and Justice Stephen G. Breyer are native Californians, but as Scalia once wrote in an opinion listing the court’s lack of geographic diversity, “California does not count.”

He also provides the court with something it has lacked since 2010: a Protestant. Gorsuch was raised as a Catholic, but he and his family attend an Episcopal church in Boulder. He joins five Catholics and three Jews on the court.

Trump is anxious to celebrate Gorsuch’s success because it is one of the few clear accomplishments of his young administration, uniting Republicans. But the work was mostly done by outside groups and Senate Majority Leader Mitch McConnell, R-Kentucky.