The Marlins will officially announce Ramirez's signing at 11 a.m. ET Saturday at the Orange Bowl site in Miami.
Marlins owner Jeffrey Loria, team president David Samson, president of baseball operations Larry Beinfest and general manager Michael Hill will be at the news conference.
According to a high-placed source familiar with the negotiations, the 24-year-old shortstop's six-year, $70 million deal will kick in next season.
Ramirez will make $5.5 million in 2009, and the deal bumps up considerably in the upcoming years.
By coming to terms now, the Marlins will lock up Ramirez through his arbitration years (2009-2011), and then three more years, where he could have qualified for free agency. For those three seasons, the shortstop will earn $23.5 million.
The Dominican Republic native will get $15 million in 2012, $15.5 million in 2013 and $16 million in 2014.
So in what could have been his first three seasons of free agency, Ramirez will collect $46.5 million.
The contract doesn't not include a no-trade clause or a signing bonus.
Ramirez, already one of the top talents in the game, is making $439,000 this season.
The deal is the richest in Marlins history. Ramirez becomes the first Florida player since the 2005 season to receive a multiyear contract.
Typically, the Marlins don't buy out arbitration years, but Ramirez is an exceptional talent, and the organization is making an exception.
With the security of a new stadium, which is expected to open in 2011 on the horizon, the Marlins clearly are showcasing Ramirez as their "franchise player."
Said Marlins manager Fredi Gonzalez of the deal: "It's not finalized yet, but I think it's great for the community and the organization. [Ramirez] has a lot of good years ahead of him, and I think it sends a message to the community."
Ramirez's numbers justify the long-term commitment.
In 2006, Ramirez was named the National League Rookie of the Year. He followed that up by batting .332 with 29 home runs and a franchise-record 125 runs scored in 2007.
The gifted shortstop continues to build incredible all-around numbers this season. The Marlins are off to their best start in history, and Ramirez is a major factor.
Making the announcement at the Orange Bowl is fitting, since the club expects to open the 2011 season in a new retractable-roof park at the site.
Joe Frisaro is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.