On Monday night, Miami reached an agreement with Diaz on a Minor League contract with an invitation to Spring Training. He will be in camp on Tuesday, and is expected to be in uniform when the Marlins face the Nationals at Roger Dean Stadium.
Diaz, primarily a corner outfielder, was released by the Yankees on March 17.
Although Opening Day is a week away -- April 1 at Washington -- Diaz will be given a quick look to see if he can make the club.
This spring with the Yankees, the veteran backup outfielder was 6-for-30 (.200) in 13 Grapefruit League games.
Diaz appeared in 51 games with the Braves last year, batting .222 with two home runs and 13 RBIs.
The Marlins are seeking a right-handed bat off the bench to complement the left-handed-hitting Greg Dobbs.
Diaz is a career .324 hitter against left-handed pitching.
The Marlins are still rounding out their roster, and they are exploring players who are being released to see if they are a possible fit.
On Saturday, the Marlins signed utility infielder Wilson Valdez, who was released on Friday by the Giants.
Diaz broke in with the Rays in 2003, and he played in 2005 for the Royals. His greatest success came with the Braves.
Diaz attended Florida State University, and he is a .291 career hitter with 45 homers.
Joe Frisaro is a reporter for MLB.com. He writes a blog, called The Fish Pond. Follow him on Twitter