WASHINGTON - Nearly three months after she won confirmation to the Supreme Court, Ketanji Brown Jackson is officially becoming a justice.

Judge Jackson, 51, will be sworn as the court’s 116th justice Thursday, just as the man she is replacing, Justice Stephen Breyer, retires.

The judicial pas de deux is set to take place at noon, the moment Justice Breyer said in a letter to President Biden on Wednesday that his retirement will take effect after nearly 28 years on the nation’s highest court.

The court is expected to issue its final opinions earlier Thursday in a momentous and rancorous term that included overturning Roe v. Wade’s guarantee of the right to an abortion. The remaining cases are a challenge to the Environmental Protection Agency’s ability to regulate climate-warming emissions from power plants, and Biden’s bid to end the Trump-era “remain in Mexico” asylum program.

In a ceremony the court said it will stream live on its website, Judge Jackson will recite two oaths required of Supreme Court justices, one administered by Justice Breyer and the other by Chief Justice John Roberts.

Judge Jackson, a federal judge since 2013, will be the first Black woman to serve as a justice. She will be joining three women, Justices Sonia Sotomayor, Elena Kagan and Amy Coney Barrett — the first time four women will serve together on the nine-member court.

President Biden nominated Jackson in February, a month after Justice Breyer, 83, announced he would retire at the end of the court’s term, assuming his successor had been confirmed. Justice 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.

She has been in a sort of judicial limbo ever since, remaining a judge on the federal appeals court in Washington, D.C., but not hearing any cases. President Biden elevated her to that court from the district judgeship to which she was appointed by President Obama.

Judge Jackson will be able to begin work immediately, but the court will have just finished the bulk of its work until the fall, apart from emergency appeals that occasionally arise. That will give her time to settle in and familiarize herself with the roughly two dozen cases the court already has agreed to hear starting in October as well as hundreds of appeals that will pile up over the summer.