Granderson, 32, met Sunday with Mets general manager Sandy Alderson in what was described as more of an introductory meeting before talks escalated quickly.
"We ate a nice meal, and it was great to enjoy some salmon," Granderson had said.
Granderson provides a second power infusion to the outfield for a team desperately in need of a power upgrade. The Mets signed former Arizona Diamondbacks and Oakland Athletics outfielder Chris Young to a one-year, $7.25 million contract last week. Last season, the Mets ranked 11th in the National League in home runs. They surrendered 22 more long balls than they produced.
Granderson, meanwhile, had 41 homers in 2011 and 43 in '12 with the New York Yankees, albeit with a more homer-friendly home ballpark in the Bronx. A broken forearm during spring training and a pinkie injury suffered during the season limited Granderson to 245 plate appearances in 2013.
The team's projected lineup also will include right-handed hitters Young, David Wright, Travis d'Arnaud, Juan Lagares and Ruben Tejada, and lefties Daniel Murphy and Lucas Duda or Ike Davis. There also is switch-hitter Eric Young Jr.
It appears Granderson will play left field, with Lagares in center and Chris Young in right. That would free up the speedy Eric Young, who led the NL in stolen bases, to play second base should the Mets trade Murphy.
The deal for Granderson is by far the biggest free-agent expenditure the Mets have made in Alderson's four offseasons as GM. The largest contract previously belonged to Frank Francisco, who signed a now-expired two-year, $12 million deal during the 2011-12 offseason.
New York's outfield combined to hit .238 this past season (29th in the majors) with 50 homers (tied for 24th) and 209 RBIs (16th), according to STATS.
Granderson turned down a $14.1 million qualifying offer from the Yankees to test the open market. The Mets, however, would not have to forfeit their first-round draft pick to sign him because they own the 10th overall selection. The top 10 picks are protected.
Granderson's numbers have declined each of the past three years, down to a .317 on-base percentage and a .407 slugging mark last season. He also is prone to strikeouts -- whiffing 364 times from 2011-12 -- and joins a Mets lineup that fanned 1,384 times this year, tied with Atlanta for most in the NL.
But his bat is a significant upgrade for the Mets, starved for offense following their fifth straight losing season since moving into Citi Field. Now, the club can focus on other areas of need -- shortstop, first base, pitching -- heading into baseball's winter meetings next week.
Granderson was on the disabled list twice last season after getting hit by pitches.
He missed the first 38 games after breaking his right wrist when he was plunked by Toronto left-hander J.A. Happ in his first plate appearance of spring training on Feb. 24. Not long after he returned, Granderson broke a knuckle on his left pinkie when he was hit at Tampa Bay on May 24.
That kept him out until August, making Granderson one of several Yankees stars to be sidelined much of the season. The Yankees were unable to overcome all the injuries, missing the playoffs for only the second time in 19 years.
Granderson's agreement with the Mets was earlier reported by the New York Post.
Information from ESPNNewYork.com's Adam Rubin and The Associated Press was used in this report.