California Gov. Jerry Brown named Becerra to the spot Thursday opened up by the departure of Kamala Harris, who won a US Senate seat this November. Becerra will need to be confirmed by California's Legislature and the nomination will be made official once Harris resigns.
Becerra is the highest-ranking Latino politician in the Democratic party and serves as the No. 4 House Democrat, as chairman of the party's caucus, though he was term-limited out of that position next Congress.
While the move will take Becerra, 58, out of congressional leadership, it also sets him up to be a major voice against the Trump administration.
Becerra was term-limited as chairman of the caucus and had no obvious path to advancing through the leadership ranks as the top three ranking Democrats, Reps. Nancy Pelosi, Steny Hoyer and Jim Clyburn, were all maintaining their spots atop the party.
He had been rumored as a possible vice presidential pick for Hillary Clinton, in part because of his strong voice in Hispanic outreach for Democrats.
Now, he'll be in a prime position to be a voice of opposition to the policies of the Trump administration and Republican Congress on a host of hot-button issues, including immigration and climate change.
In a call with reporters about his move, Becerra framed much of his new job in terms of standing up to the Trump administration, if necessary, though he did not outright state it in terms of Trump.
"The federal government isn't going to be as much of a friend to California, and I hope doesn't become a foe to California, but we have to be prepared to defend the forward-leaning progress that California has made for its people," Becerra said of the new landscape.
He listed his priorities as clean energy -- "I want to be vigorous in defense of what we've done and support the efforts to take us farther" -- and protecting all people, including immigrants -- "I want to make sure that public safety applies to all of them and that people know they will be safe in their homes and their neighborhoods."
Becerra added that he would stand up for Obamacare and criminal justice reform.
"I would hate to see the federal government do anything that would undermine the progress we've made to make sure the justice system is fair," he said.
He was a fierce opponent of President-elect Donald Trump on the campaign trail -- especially for his anti-immigration rhetoric and comments about Mexicans during the campaign, including using the term "rapists," and questioning the impartiality of a federal judge due to his Mexican heritage.
"Donald Trump is saying that a respected jurist who was confirmed by a bipartisan vote in the Senate is incapable of serving because of his Mexican heritage," Becerra told CNN's Jake Tapper on "State of the Union" in early June. "I think that's racist. We should call it that."
A deeply blue state, California is a key player in both debates, and would likely oppose the Trump administration on hard-line deportation or anti-immigration policies as well as rolling back regulations designed to fight climate change.
The post was a launching pad for Harris, who parlayed her high profile role into a Senate seat this fall and has been a rising star within the Democratic Party.
"I think we're going to see Rep. Becerra be at the forefront of these issues that affect Latinos throughout the country," said César Blanco, political director of Latino Victory Project.
"If this Congress and this President-elect decides to move forward on any sanctuary city, you will see several states push back on protection for immigrants and immigrant rights," Blanco added. "Xavier Becerra, you couldn't find a better advocate or someone who could fight with so much depth and knowledge of immigration policy in this country, and being the top attorney of the state of California puts him in a good position to push back on some of these policies what we may see moving forward."
Leaving Capitol Hill "doesn't stop (Becerra) from having an important voice," said Yvanna Cancela, executive director of the Nevada Citizenship Project and a prominent voice in Democratic politics.
"Under a Trump administration and because California is such a diverse state, Latino politics as it relates to immigration and the economy will inevitably come up," she said. "When you have leaders like Becerra, to lose them in DC is a shame for DC and for the country, but it is really exciting to have him in such a high leadership role in California."
Cancela said Becerra would be "a strong voice in the state but also a strong voice nationally for creative and really thoughtful policies that protect people from egregious anti-immigrant policies that might come out of DC."
Brown lauded Becerra in a statement and especially highlighted his ability to work on climate change.
"Xavier has been an outstanding public servant - in the State Legislature, the U.S. Congress and as a deputy attorney general," Brown said. "I'm confident he will be a champion for all Californians and help our state aggressively combat climate change."