President Joe Biden has nominated Judge Ketanji Onyika Brown Jackson to the Supreme Court, calling her "one of the nation's brightest legal minds".
She will be the first black woman to serve in the court's 232-year history if confirmed.
She would replace liberal Supreme Court Justice Stephen Breyer when he retires at the end of the court's term in June.
Ms Jackson is a federal appeals judge, who has worked as a public defender.
"Judge Jackson is an exceptionally qualified nominee as well as an historic nominee, and the Senate should move forward with a fair and timely hearing and confirmation," the White House said in a statement on Friday.
With the Senate divided 50-50 between the parties, Democrats have just enough votes to confirm President Biden's choice if they all back her. Vice President Kamala Harris has the deciding vote.
Justice Breyer's replacement would not shift the court's current 6-3 conservative majority.
The Supreme Court plays a key role in American life and is often the final word on highly contentious laws, disputes between states and the federal government, and final appeals to stay executions.
For any Supreme Court justice nomination, the president first chooses his preferred candidate and the Senate then votes to confirm that nominee, which requires a simple majority.
Senate Majority Leader Chuck Schumer said Senate Judiciary Committee will begin hearings "in the coming weeks".
Ms Jackson, 51, currently serves on the influential US Court of Appeals for the DC circuit. Three current supreme court justices previously served on that court.
The jurist has two degrees from Harvard University, which she attended as an undergraduate and as a law student, and once served as editor of the Harvard Law Review.
Mr Biden first promised to nominate an African American woman to the top court two years ago while campaigning for the Democratic presidential nomination.
"I'm looking forward to making sure there's a black woman on the Supreme Court, to make sure we, in fact, get every representation," he said at the time. Last month, he called the nomination of a black woman "long overdue".
Black women make up about 3% of the federal judiciary, according to data from the Federal Judicial Center, the court system's research arm.
Mr Biden's nomination of Ms Jackson is historic for more than one reason. If she is nominated, four women may sit together on the nine-member court for the first time.
Ms Jackson was born in Washington, DC but grew up in the Miami are
At her 2021 confirmation to the appellate court, she credited a background of public service with her decision to work as a public defender. Her parents are both graduates of historically black colleges who began their careers as teachers, and her brother was a police officer who served in the military.
"Being in the public defenders' office felt very much like the opportunity to help with my skills and talents," she said at the time.
Ms Jackson has a connection with the justice she will replace. She clerked for Justice Breyer during the Supreme Court's 1999-2000 term.
She worked a number of legal jobs early in her career, including as a staff member for the United States Sentencing Commission. In 2012, then President Barack Obama nominated her to serve as a district court judge in Washington, DC.
During the eight years she spent on the district court, she penned more than 500 opinions. Among them, she ruled that Donald F McGhan II, the former White House counsel to President Donald Trump, had to testify in the Russia meddling probe.
"Presidents are not kings," she wrote in the 2019 ruling.
Ms Jackson, a liberal justice, has a familial connection to a Paul Ryan, former House Speaker and ex-Republican vice-presidential candidate.
At a 2013 hearing for her district court nomination, Mr Ryan, who is a a relative by marriage to Ms Jackson, introduced her to lawmakers.
"Our politics may differ, but my praise for Ketanji's intellect, for her character, for her integrity, it is unequivocal," he said.
Ms Jackson's husband is a surgeon and she has two children.
Kentanji Brown Jackson was considered the favourite to be Joe Biden's Supreme Court nominee when his search began last month - and it was a position she never relinquished.
That fits with the way Mr Biden has gone about making his other key appointments, for vice-president and top Cabinet posts. He tends to opt for the safe, predictable choice.
Ms Jackson has already been confirmed by this US Senate once, when the president nominated her to an appellate court judgeship. Although her judicial record will be scrutinised in the days ahead, it is liberal but not extreme.
Her credentials - Ivy League law school, a clerkship with retiring Supreme Court Juhstice Stephen Breyer and eight years as a federal district court judge - are high caliber.
A small drama that is sure to unfold with this pick is one between the president and Jim Clyburn, the South Carolina Democrat whose support was pivotal to Mr Biden's victory in the 2020 Democratic primaries
Mr Clyburn had his own favourite, South Carolina judge, J Michelle Childs. But Ms Childs was a more unconventional pick, without Ms Jackson's rarified academic pedigree. Picking her may have been politically helpful for Mr Biden, but that's not how this president works.