Hegseth, who has faced allegations of drunkenness and other personal misconduct, suffered three Republican defections and was voted in only with Vice President JD Vance casting a tie-breaking vote.
Hegseth, a former Fox News host, was sworn in by Vance who officiated the ceremony.
“Congratulations to Pete Hegseth. He will make a great Secretary of Defense!” President Trump wrote on Truth Social Friday night. (edited)