The club has not confirmed the reports, although ESPN -- citing an undisclosed source -- said the deal is likely to be announced "in the coming days."
Financier Bruce Sherman will hold the controlling interest and plans for Jeter to be the team's chief executive officer, the Miami Herald reported. Jeter reportedly is investing approximately $25 million of his own money.
The $1.2 billion price tag of the sale is the second-highest in a history for a Major League Baseball team, behind only the Los Angeles Dodgers' $2 billion sale in 2012.
Earlier this year, Jeter was partnering with Jeb Bush in his bid to buy the Marlins, but the former Florida governor dropped out in late May, according to multiple media reports.
Loria purchased the team in 2002 for $158 million, and a year later, the then-Florida Marlins won their second World Series. The Marlins haven't been back in the playoffs since, and they haven't finished above .500 since 2009.