Mr Holder has condemned waterboarding as torture
President Barack Obama's choice for attorney-general, Eric Holder, has been confirmed in the post by the US Senate.
Senators voted 75 to 21 to approve Mr Holder, 57, who is the first African-American to hold the office.
Mr Holder will oversee efforts to close the Guantanamo Bay prison camp, a move Mr Obama has singled out as a priority.
There had been some initial opposition to the choice of Mr Holder, who had served as a deputy attorney-general under President Bill Clinton.
In 2000, Mr Holder controversially advised President Clinton - on the last day of his administration - that he was "neutral, leaning towards favourable" about pardoning fugitive financier Marc Rich.
1951: Born in New York City
1976-88: Justice department's public integrity section
1988-93: Superior Court judge
1993-97: US Attorney for District of Columbia
1997-2001: Deputy attorney general
2001-2009: Private legal practice
Critics accused the outgoing president of issuing the pardon because Mr Rich's wife had donated money to Mr Clinton's presidential library.
Mr Holder has said during his confirmation hearings that he made a mistake in that case.
Mr Holder, who is a former federal judge and US prosecutor, will oversee a review of US legal policy in the war on terrorism, including interrogation tactics.
During his confirmation hearings, he condemned the practice of waterboarding, a technique which creates the sensation of drowning.
"If you look at the history of the use of that technique, we prosecuted our own soldiers for using it in Vietnam," he said. "Waterboarding is torture."