Pope Francis has appointed 13 new cardinals, including the first African American man to hold the role.
Wilton Gregory was installed at a ceremony in the Vatican, with participants donning face masks and some appearing via video link.
The 72-year-old Archbishop of Washington DC was announced as one of the new cardinals last month.
The red-robed cardinals are the most senior clergymen in the Roman Catholic Church after the Pope himself.
Their role includes electing the pope - the head of the Church - who is chosen from among them at a secret gathering known as a conclave.
As four of the new intake are over the age of 80, they will not be allowed to vote at a future conclave under Church rules.
The nine new cardinals who will be eligible to vote - aside from US citizen Wilton Gregory - come from Italy, Malta, Rwanda, the Philippines, Chile, Brunei and Mexico.
The ceremony, known as a consistory, was slimmed down due to the coronavirus. Everyone present wore a mask except for Pope Francis, and each new cardinal removed their face covering when they bent down before the pontiff to be invested.
The Argentinian pontiff, who has led the church since 2013, has now appointed more than half the 128 cardinal electors.
Who is Wilton Gregory?An ordained priest since the age of 25, he became Washington's archbishop in May 2019. He replaced Cardinal Donald Wuerl, who resigned amid criticism of his handling of abuse cases.
In the US, Cardinal Gregory has been a prominent voice in the effort to root out abuse within the Church. As president of the US bishops' conference, he persuaded Church leaders to adopt tougher penalties for abusers in 2002.
Cardinal Gregory has been critical of President Donald Trump over his use of rhetoric and visits to religious sites.
He rebuked President Trump's visit to a shrine to St John Paul II in Washington, calling it "baffling and reprehensible".
The visit came in June, a day after the president had ordered the dispersal of peaceful protesters near the White House.
The archbishop said St John Paul II "certainly would not condone the use of tear gas and other deterrents to silence, scatter or intimidate [protesters] for a photo opportunity in front of a place of worship and peace".
Some conservative Catholics criticised him for the remarks.