The 6-4, 325-pound McIntosh is a four-year veteran who has started 37 games for the Chargers over the past three seasons.
The Dolphins began giving serious consideration to McIntosh after John Tait of Kansas City, Miami's first choice at tackle, signed an offer sheet to play with the Bears.
Other new players who will be with the team this season are cornerback Reggie Howard and safety Chris Akins. Both were signed this past weekend.
Howard, who signed a six-year, $21.6 million contract, was an undrafted player in 2000 who was claimed off of waivers by Carolina that season. He started every game for the Panthers this past year, recording three interceptions and 10 pass breakups for the NFC champions.
He becomes the second Carolina starter that the Dolphins have signed in the last week, the other being guard Jeno James.
The 5-11, 200-pound Akins was signed from New England and is mainly thought of as a special teams player.
Miami also lost two players over the weekend, as fullback Obafemi Ayanbadejo signed with Arizona and linebacker Tommy Hendricks signed with Jacksonville. Both were key backups and excellent special teams players.
One special teams player that the team did keep was safety Shawn Wooden, who re-signed with the team with a one-year deal.