The Saints made the decision to place Thomas on injured reserve a few weeks ago to buy him time to get healthy for the postseason.
Thomas has been dealing with an ankle injury that he suffered earlier on in the season.
This opens a three-week window of time for the Patriots to activate him from injured reserve and add him to their 53-man roster.
Thomas, 27, was drafted by the Saints in the second round out of Ohio State in 2016. He was entering the final year of a four-year, $5.118 million rookie contract when he agreed to a five-year, $100 million extension last July.
In 2020, Thomas has appeared in seven games for the Saints and caught 40 passes for 438 yards receiving and no touchdowns.