Ketanji Brown Jackson has become the first Black woman sworn in to the highest court in the US.
The 51-year-old is the court’s 116th justice and she took the place of the judge she once worked for, Justice Stephen Breyer, whose retirement took effect at midday.
Moments later, joined by her family, Judge Jackson recited the two oaths required of Supreme Court justices, one administered by Mr Breyer and the other by Chief Justice John Roberts.
“With a full heart, I accept the solemn responsibility of supporting and defending the Constitution of the United States and administering justice without fear or favour, so help me God,” Judge Jackson said in a statement issued by the court.
“I am truly grateful to be part of the promise of our great nation. I extend my sincerest thanks to all of my new colleagues for their warm and gracious welcome.”
Mr Roberts welcomed the newest justice “to the court and our common calling.”
Judge Jackson, a federal judge since 2013, is joining three other women, Justices Sonia Sotomayor, Elena Kagan and Amy Coney Barrett, which is the first time four women will serve together on the nine-member court.
President Joe Biden nominated Ms Jackson in February, a month after Mr Breyer, 83, announced he would retire at the end of the court's term, assuming his successor had been confirmed.
Mr Breyer's earlier-than-usual announcement and the condition he attached was a recognition of the Democrats' tenuous hold on the Senate in an era of hyper-partisanship, especially surrounding federal judgeships.
The Senate confirmed Judge Jackson's nomination in early April, by a 53-47 mostly party-line vote that included support from three Republicans.
Who is Judge Ketanji Brown Jackson?
Judge Jackson, 51, was born in Washington DC but grew up in Miami.
When she was in school in Florida, she told a guidance counsellor she wanted to attend Harvard. The counsellor reportedly replied that she shouldn't aim "so high".
She would go on to study at Harvard College and Harvard Law School, graduating with distinction.
After finishing law school, she worked for Justice Stephen Breyer - whose seat she takes on the court.
She has praised his legacy, saying he "exemplifies what it means to be a Supreme Court justice of the highest level of skill and integrity, civility and grace".
Judge Jackson then spent two years serving as a public defence lawyer, representing those who could not pay for a lawyer.
In 2012, she was nominated by President Obama to serve as a District Judge for the District of Columbia - a role she worked in until 2021.
Last year, President Biden nominated her to become a Judge on the US Court of Appeals, which was her most recent role.
The Supreme Court is dominated 6-3 by conservative Justices but she will join the liberal side.
She lives with her husband and two daughters in Washington DC.
Democrats on the Judiciary Committee, which holds Supreme Court hearings, praised Judge Jackson for her record.
Democratic Senator Mazie Hirono told the hearing: "Let me be clear your nomination is about not about filling a quota. It is about time. It's about time that we have a highly qualified, highly accomplished black woman on the Supreme Court."