Brown recited the Judicial Oath back to Jackson as he officially became a retired justice and she took her post following her confirmation earlier this year.
Ketanji Jackson Brown has been sworn in as the first black female Supreme Court justice.
She was sworn in on Thursday by Justice Stephen Breyer, whose seat she is taking with his retirement from the bench.
Brown recited the Judicial Oath back to Jackson as he officially became a retired justice and she took her post following her confirmation earlier this year.
Breyer's final term saw several controversial decisions with the new 6-3 conservative majority following the death of Ruth Bader Ginsburg.
The consequential term saw the landmark abortion case Roe v. Wade overturned.
The justices gathered Thursday for the swearing-in ceremony after their final two opinions of the term were issued on Thursday – including one that upheld President Joe Biden's move to terminate the Trump-era Migrant Protection Protocols (MPP).