US Republicans have appointed New York Congresswoman Elise Stefanik, a Trump loyalist, to the third-ranking post in the House of Representatives.
It follows an earlier vote to oust the incumbent chairwoman, Liz Cheney, from the role over her criticism of former President Donald Trump.
The final tally of Friday's secret ballot was 134 for Ms Stefanik to 46 for her opponent, Congressman Chip Roy.
Ms Stefanik's win was expected, as she had the backing of top Republicans.
The move is seen as a sign Mr Trump's grip on the party is as strong as ever six months after he lost the election.
"Thank you to my colleagues for electing me to serve as House Republican Conference Chair," Ms Stefanik wrote on Twitter after the vote.
"I am excited to lead our unified team... to combat Biden and Pelosi's Far-Left agenda!" she added, referring to President Joe Biden and Democratic Speaker of the House Nancy Pelosi.
In remarks to reporters, Ms Stefanik said her predecessor - who is the daughter of ex-US Vice-President Dick Cheney - remained "a part of this Republican conference".
Ms Cheney fell afoul of her party earlier this year, as she was one of 10 Republicans who voted with Democrats to impeach then-President Trump for inciting the 6 January Capitol riot. He was eventually acquitted in the Republican-controlled Senate.
Ms Stefanik added on Friday that "we are united in working with President Trump", calling the former president a "critical part of our Republican team".
As chairwoman, she will oversee day-to-day operations for the Republican conference, which meets regularly to determine committee assignments for lawmakers and produces fact sheets and materials to keep the party's message unified.
What have Republicans said about her?
Mr Trump issued a statement congratulating Ms Stefanik on her "overwhelming victory" and saying the "Make America Great Again movement is strong".
Republican House Leader Kevin McCarthy congratulated Ms Stefanik and Mr Roy, saying: "We had a healthy debate and a good election. We've got a lot of work to do in this leadership team, in this conference."
Congressman Steve Scalise, the second-highest ranking House Republican, also praised Ms Stefanik, adding that the party "is incredibly unified".
Mr Roy, a hardline conservative who had said he was running because Ms Stefanik's credentials were not strong enough, hailed the conference's voting process and congratulated his rival.
"It's time for us to move forward with a vision and a plan to fight for the forgotten men and women of this country, their way of life, and the principles - built upon the bedrock of freedom - that have made it great," he added in a statement.
Who is Ms Stefanik?
In 2014, the New York lawmaker became the youngest woman ever elected to Congress.
Then 30-years-old, she billed herself to voters as a traditional conservative with an independent streak. In her first major bid for public office, Ms Stefanik flipped a Democratic-controlled seat in upstate New York and claimed a more than 20-point victory.
Before running for office, she worked for the George W Bush White House and for former Republican Speaker of the House Paul Ryan.
Ms Stefanik criticised Mr Trump during his campaign on numerous issues. Later, her opposition to Trump-backed policies, including his border wall and tax cuts, earned her low ratings from conservative watchdog groups.
But she became one of Mr Trump's top defenders during his first impeachment trial, with her clashes with Democrats frequently going viral in conservative media.
In 2019, Mr Trump decreed on Twitter: "A new Republican Star is born."