The US Senate on Friday confirmed Joe Biden’s nominee, Lloyd Austin, to serve as the secretary of defense, making the retired four-star army officer the first African American to lead the Pentagon. The final vote was 93 to 2, with only two Senate Republicans – Mike Lee of Utah and Josh Hawley of Missouri – opposing Austin’s nomination. Austin said in a tweet that it was “an honor and a privilege” to serve as the defense secretary, adding that he was “especially proud” to be the first African American to hold the position. “Let’s get to work,” he wrote. Austin, 67, will oversee the 1.3 million active duty men and women who make up the nation’s military. The Senate vote gave Biden his second cabinet official, and another crucial member of his national security team, after Avril Haines was confirmed on Wednesday as the first woman to serve as the director of national intelligence. She was sworn in on Thursday by the vice-president, Kamala Harris. Austin’s confirmation required a special dispensation from both chambers of Congress, waiving a legal prohibition on military officials serving as secretary of defense within seven years of their retirement from active-duty service. The House and Senate easily approved the waiver on Thursday, despite concerns among some lawmakers about granting an exception from a law intended to maintain civil control of the military. It was only the third time Congress had granted the exception, including in 2017 for the retired marine general Jim Mattis to become Donald Trump’s first defense secretary in 2017. Austin sought to allay concerns over his recent service during his confirmation hearing, saying he was a “general and a soldier” who was prepared “to serve now – as a civilian – fully acknowledging the importance of this distinction.” Austin, raised in a rural town in Georgia, graduated from West Point and steadily rose through the nearly all-white ranks of the military, breaking racial barriers nearly every step of the way during his decorated 41-year career. In a video posted on Twitter, he reflected on the historic nature of his nomination and vowed that he “won’t be the last” African American to lead the military. Appearing before the Senate armed services committee this week, Austin was asked how he planned to address rightwing extremism and white nationalism within the military, particularly as officials investigate the involvement of current and former service members in the violent attack on the US Capitol. Austin said he was committed to rooting out domestic extremism, telling lawmakers: “The job of the Department of Defense is to keep America safe from our enemies. But we can’t do that if some of those enemies lie within our own ranks.” Biden nominated Austin to restore stability atop the Pentagon and to rebuild America’s relationship with allies, frayed by the Trump administration, and orient the defense department to confront threats ranging from potential future pandemics to the climate emergency to refugee crises. “In my judgment, there is no question that he is the right person for this job at the right moment, leading the Department of Defense at this moment in our nation’s history,” Biden said as he announced his nomination of Austin for the role last month. He called Austin the “definition of duty, honor and country” and a leader “feared by our adversaries, known and respected by our allies”. Shortly after he was sworn in on Friday, Austin made his first official phone call to the Nato secretary general, Jens Stoltenberg, to reiterate the country’s “steadfast commitment” to the defense alliance that had been a target of Trump’s wrath for nearly four years. The White House press secretary, Jen Psaki, said he would be sworn in “more ceremoniously” by Harris on Monday. The Senate finance committee also unanimously supported the nomination of Janet Yellen for treasury secretary on Friday morning, setting up a final confirmation vote. Chuck Schumer, the Senate majority leader, said the full chamber would vote on her confirmation on Monday. • This article was amended on 22 January 2020. An earlier version referred to Lloyd Austin as a retired marine officer; he is a retired army general.