Lo Duca will report to Triple-A Albuquerque on Saturday, and will likely catch and serve as a designated hitter. He said there is no timetable as to when he'd be called up to the Majors.
This will be the second stint with Florida for Lo Duca, 36, who was released by the Nationals on July 31.
Lo Duca joined with the Marlins in July 2004 in a trade that sent pitcher Brad Penny to the Dodgers. After the '05 season, Florida dealt him to the Mets.
The Marlins are currently going with John Baker and Matt Treanor as their primary backstops, and after some time in the Minors, Lo Duca could see time behind the plate for Florida in a September callup.
"I'm not here to buck the trend," Lo Duca said. "John and Matt have done an excellent job. I just want to be a guy who can make a contribution."
Lo Duca appeared in 46 games for the Nationals this season. He was hitting .230 over 139 at-bats before being released. He also dealt with a right wrist injury that landed him on the disabled list.
With 1,061 career games under his belt, there are questions about Lo Duca's throwing arm behind the plate.
"I'm healthy now," said Lo Duca, who has been staying in New York since he was released. "My hand is healthy. I'm ready to [go]. I don't think that is going to be an issue."
In 2004, Lo Duca played in 52 games for Florida, batting .258 with three home runs and 31 RBIs. Lo Duca's lone full season with the Marlins was in 2005, when he appeared in 132 games, batting .283 with six home runs and 57 RBIs.
Treanor developed a friendship with Lo Duca.
"Paul is a veteran guy, he's real intelligent," Treanor said. "He taught me a lot when I was here. Little things you should pay attention to in games. Just little things about other teams. Game situations. That's what he brings."