His agents, Drew and Jason Rosenhaus, confirmed Monday morning that Brown agreed to a two-year deal with the franchise.
Trading Mason, along with Brown's return, helps solidify where third-year tackle/guard Mike Onwenu will play this season. Onwenu projects as a starting guard.
When the Patriots acquired Brown from the Las Vegas Raiders in March 2021, it marked the second time the team traded for him (the 49ers also dealt him to the Patriots in 2018). Brown is just the fourth NFL player since 1980 to be traded to the same team multiple times, joining Jerome Harrison (Eagles, 2010, '11), Mark Hermann (Colts, 1983, '88) and Walter White (Cardinals, both times in 1980).
The 6-foot-8, 380-pound Brown was sidelined by a calf injury that he sustained on the opening series of last season. He missed the next eight games, before settling into a starting role at right tackle upon his return, finishing the year with nine straight starts (including playoffs) and helping solidify New England's offensive line as one of the strengths of the team.
Brown's 2019 and 2020 seasons with the Raiders had been similar in terms of injuries (and a COVID-19 absence), as he appeared in just 16 of a possible 32 games.
Upon his return to New England in 2021, Brown had said: "I've worn a lot of jerseys in my life, but I have never been more proud than when I put on a Patriots jersey."
Brown, who turns 29 on April 13, has experience at both right and left tackle in seven NFL seasons.
ESPN's Mike Reiss contributed to this report.