Scaramucci said he met with Trump last week at the candidate's New York office. "I am on board and will support and raise money for him," he said. "I will do whatever I can to support our Republican nominee."
Scaramucci previously served as a national finance co-chairman for Mitt Romney's 2012 campaign and for Wisconsin Gov. Scott Walker's 2016 campaign. Soon after Walker dropped out in the fall, he signed on with Jeb Bush's campaign, joining the former Florida governor's national finance committee.
Both Romney and Bush have said they would not support Trump in the November election, while Walker endorsed and campaigned enthusiastically for Trump's top primary opponent, Sen. Ted Cruz of Texas.
The Trump finance team is chaired by Steven Mnuchin, who like Scaramucci has deep ties on Wall Street and in the broader financial industry.
Scaramucci is founder and co-managing partner of SkyBridge Capital, a global investment firm, and also works as a host and contributor on FOX Business Network. He confirmed his role with the Trump campaign while flying Monday afternoon to Las Vegas, where he hosts the SkyBridge Alternatives Conference, a major annual gathering of hedge fund managers and financial titans that begins on Tuesday. He said he and Mnuchin plan to huddle with potential Trump donors at the conference, known as SALT.
"I look forward to working with Steve Mnuchin to build out the team," Scaramucci said. He predicted the Trump campaign will raise a "historic" sum of money. "Starting from a standing start, we will surprise people to the upside. Steve is a very creative guy."
A Trump campaign spokeswoman had no comment.
Trump and Scaramucci made headlines in August after Trump attacked hedge fund operators by saying they are "getting away with murder." Scaramucci, then running Walker's fundraising operations, publicly criticized the celebrity candidate. The two met at Trump Tower a few days later to make amends, with Scaramucci saying he asked Trump in the meeting to stop taking swipes at his industry and Trump telling the Wall Street Journal that Scaramucci suggested to him that he might endorse him.
In the months since, Scaramucci has warmed to Trump. Last week, with Trump on the cusp of securing the nomination, Scaramucci said on National Public Radio that it was time for Republican leaders to embrace Trump.
"I speak as a person who has gone 0 for 2 in this process," Scaramucci said on NPR. "I was with Gov. Walker. That didn't work out for me. I was with Jeb Bush. That didn't work out for me. And so, you know, my point is that I'm a team-playing Republican. I'm hoping that whatever soreness he's inflicted upon others, people will put that aside and they will become team oriented and coalesce around him."