According to Adam Schefter, Thomas will go to Baltimore on a four-year, $55 million dollar deal and will be the 4th highest paid safety in the NFL (Spotrac).
Thomas was limited to four games last season after suffering a broken leg.
Rumors circulated Tuesday night that Thomas was talking with the Cleveland Browns.
During the 2018 season, the safety was headed into the final year of his contract with the Seahawks that was set to pay him $8.5 million in base salary.
Thomas leaves Seattle going down as one of the three best safeties in team history along with Hall of Famer Kenny Easley and Chancellor, with whom he helped form the famed Legion of Boom defense from 2010 until Chancellor's career-ending injury against Arizona on November 9, 2017.
The Seahawks did more subtracting than adding the first few days of free agency, most notably losing their best defensive player, free safety Earl Thomas.
Thomas was a first-team All-Pro pick three times.
During Thomas' best years in Seattle, the Seahawks had six consecutive winning seasons, three division titles, and two NFC championships along with their Super Bowl title.
Since entering the National Football League in 2010, Thomas has been an absolute ball-hawk and the ostensible quarterback of the Seahawks' defense.