Fifty-one-year-old's appointment by Democratic President Joe Biden means white men are not in the majority on the nation's Supreme Court for the first time in 233 years.
The United States has made history after Ketanji Brown Jackson was sworn in as the first Black woman to serve on the Supreme Court.
"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," Jackson said in a statement on Thursday.
"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."
Jackson, a federal judge since 2013, is joining three other women — Justices Sonia Sotomayor, Elena Kagan and Amy Coney Barrett. It’s the first time four women will serve together on the nine-member court.
"I am pleased to welcome Justice Jackson to the court and to our common calling," Chief Justice John Roberts said at the ceremony.
"As Justice Ketanji Brown Jackson takes her seat on the Supreme Court, our nation takes a historic step toward realising our highest ideals," Nancy Pelosi, the top Democrat in Congress, said in a statement.
"Amid this court's cruel assault on Americans' health, freedom and security, she will be a much-needed force for equal justice for all."
The 51-year-old's appointment by Democratic President Joe Biden means white men are not in the majority on the nation's highest court for the first time in 233 years.
While her confirmation is a milestone, it won't change the 6-3 conservative majority on the court, which has come under fire for recent rulings broadening the right to bear arms, eviscerating abortion rights and limiting the government's power to curb greenhouse gases.
She had picked up support from three Senate Republicans during a gruelling and at times brutal confirmation process, delivering Biden a bipartisan 53-47 approval for his first Supreme Court nominee.
Justice Ketanji Brown Jackson.— President Biden (@POTUS) June 30, 2022
As I said the day she was confirmed: You’d be hard-pressed to find someone better qualified for the job. Congratulations, Justice Jackson. pic.twitter.com/HVDVPB74ZZ
Biden's major moment
Biden has aimed to bring more women and minorities and a wider range of backgrounds to the federal judiciary. Jackson's appointment fulfilled a pledge Biden made during the 2020 presidential campaign to name a Black woman to the Supreme Court.
With Jackson's addition, the Supreme Court for the first time has four women on the bench.
Jackson's swearing-in marks a major moment for Biden, who chaired the Senate Judiciary Committee in the 1980s and 90s, meaning he has the unprecedented distinction of both naming and overseeing the appointment of a Supreme Court justice.
The appointment presents an opportunity for his administration to pivot from a spate of bad news in recent months, with Biden's poll ratings still languishing below 40 percent amid runaway inflation ahead of midterm elections in November.
Crucially, it has allowed Biden to show the Black voters who rescued his floundering 2020 primary campaign that he can deliver for them.
At 42 days, the confirmation was among the shortest in history, although longer than it took to seat Donald Trump's last court pick during his presidency, Amy Coney Barrett.
As the final word on all civil and criminal legal disputes, as well as guardian and interpreter of the Constitution, the Supreme Court seeks to ensure equal justice under the law.
Four of the justices on the nine-member court are now women, making it the most diverse bench in history –– although they all attended the elite law schools of Harvard or Yale.