Jimmy Graham scored late in the first half in a defense-dominated win for the Seahawks (3-2), who shut out the NFL's highest-scoring offense in the second half of their second straight win over their NFC West rivals.
Thomas made enormous defensive plays early and late for Seattle. The veteran safety stripped the ball from Todd Gurley at the goal line to kill the Rams' opening drive, and he intercepted Jared Goff's fluttering pass at midfield with 6:02 to play.
Sheldon Richardson also came through with two big plays, diving to intercept a deflected pass in the third quarter before scooping up Goff's fumble near midfield with 2:45 left.
Goff moved the Rams 55 yards in the final 1:09, but Seattle's defense made its final stop. Rams rookie Cooper Kupp barely missed a diving TD grab on third down, and Goff's fourth-down pass to Kupp was too low.
Tavon Austin rushed for a 27-yard TD for Los Angeles (3-2), and Goff went 22 of 47 for 288 yards with three costly turnovers.
After a quick start to the season that caught the attention of the NFL and their own home market, the Rams wasted their strong defensive game when new coach Sean McVay's offense ran into the Legion of Boom.
Wilson put on a performance of vintage resourcefulness, repeatedly wriggling away from the Rams' pursuing defense to make plays. Blair Walsh's two second-half field goals turned out to be the difference.
Austin, the wide receiver used more often as a ball carrier by McVay, scored the game's first points when he took a handoff and high-stepped to the end zone early in the second quarter.
Wilson then threw an interception to Rams rookie John Johnson, who returned it 69 yards . The Rams led 10-0 on Greg Zuerlein's ensuing field goal, but the Seahawks mounted a 15-play drive culminating in Graham's short TD catch 1:55 before halftime.
The normally reliable Zuerlein missed a 36-yard field goal in the third quarter.
Thomas barely stopped the Rams' impressive opening drive when he chopped the ball out of Gurley's hand while the running back stretched toward the pylon. On video review, officials ruled Gurley had fumbled for a touchback an instant before stepping out of bounds.
Thomas made an incredibly similar play against the St. Louis Rams in 2014, chopping the ball out of Benny Cunningham's hand at the goal line.
Seahawks: DE Michael Bennett went to the locker room late in the first half after injuring his right foot. He returned for the second half, keeping Seattle sound at the position while playing without injured Cliff Avril and Quinton Jefferson.
Seahawks: At New York Giants on Sunday.
Rams: At Jacksonville on Sunday before traveling to London.
For more NFL coverage: http://www.pro32.ap.org and http://www.twitter.com/AP-NFL
Jordan Reed, who has missed seven games this season with a hamstring injury and battled a toe fracture and hip issues, ended up on injured reserve Tuesday, along with Byron Marshall and Chris Carter, giving Washington 18 players on IR.
Stephania Bell breaks down the latest on Tyrod Taylor's recovery from a knee injury.
The Patriots are close to a deal with wide receiver Kenny Britt, who was waived by the Browns on Friday. The former first-round pick has been dogged by off-field issues. At 6 feet 2, he'd give QB Tom Brady a bigger target.
Steelers coach Mike Tomlin says lying in a hospital bed hasn't stopped LB Ryan Shazier from game-planning.
Robert Griffin III joins NFL Live and expresses his goal for next season is to return to the NFL.
Robert Griffin III says he received interesting offers to play this season, including workouts with the Chargers and an opportunity to play in the Ravens' first preseason game, but opted to wait and prepare himself for 2018.