Adam Schefter of ESPN reported word of the pact with the veteran wide receiver.
Marshall started the 2018 season with the Seattle Seahawks and was having a decent campaign in limited duty with 136 yards and one touchdown on 11 receptions in six games.
The Seahawks gave David Moore a bigger role in the offense, though, and they released Marshall on Oct. 30. However, the 34-year-old had showed his health wasn't an issue after he was limited to five games in 2017 because of an ankle injury.
Following Marshall's release, Schefter reported the six-time Pro Bowler "absolutely" wanted to keep playing. He also received a vote of confidence from Seahawks head coach Pete Carroll, per 247Sports' Derek Lewis:
"He did such good stuff, helped guys on both sides of the football with all of his experience and all that. He's in terrific shape for this stage of his career and he can still play. It just happened that we looked at the roster [and] we looked at the way we're running the football. We needed a little bit more help across the board with [special] teams and some stuff that would help us in general.
"There's just not enough throws to get it to him, but he can play, and in the event where something came down and we had a chance, we'd love to have him back. We just had to do something right now, and it's unfortunate."
In his last full season in 2016, Marshall registered 788 yards on 59 receptions for the New York Jets, and he can still make catches underneath in traffic to keep the chains moving.
The Saints' revolving door at wide receiver presented the best opportunity for Marshall. Despite Michael Thomas' excellent play, New Orleans has been seeking stability on the outside, as Ted Ginn Jr., Tommylee Lewis and Cameron Meredith are on injured reserved.
Dez Bryant signed a one-year deal with the Saints on Wednesday, but his season ended Friday when he tore his Achilles during practice.
Marshall figures to have ample opportunity with Drew Brees under center, as Brees' 77.3 completion percentage would shatter his personal record of 72.0 percent, which he set last year.
The Saints are 8-1 without depth at wide receiver, and Marshall will give them stability as they chase home-field advantage in the playoffs.