The defending Super Bowl champs came back to beat Denver 41-36 on a touchdown in the final 2:58 Monday night.
St. Louis drove 61 yards in eight plays for its winning score. Warner's sideline completion to Holt came on third-and-17 from the 50 after a sack for a 7-yard loss.
The Seahawks lost in their home opener after getting shut out last week in Miami, but they put a scare into the Rams.
Jon Kitna, nearly benched by coach Mike Holmgren this week, was 20-for-31 for 245 yards with one touchdown and two interceptions.
Seattle tied it at 34 on a 34-yard pass to rookie Darrell Jackson with 2:05 left. The drive was kept alive when officials ruled Kitna wasn't intercepted by Grant Wistrom at the Seattle 24 after examining replay.
The Rams went ahead 34-27 when safety Devin Bush ran in a fumble with 5:12 left. Todd Collins sacked Kitna, causing the fumble, and Kevin Carter caught the ball in the air, running 2 yards before fumbling to Bush.
Ricky Watters' 1-yard touchdown plunge with 7:40 to go tied the score at 27 after Warner passed 4 yards to Roland Williams for a TD, his 14th consecutive completion. That had put the Rams ahead 27-20.
In the third quarter, the lead changed hands twice before Seahawks rookie Kris Heppner tied it at 20 with a 43-yard field goal.
Seattle scored its first offensive touchdown of the season on Watters' 3-yard run on the opening drive of the second half. St. Louis came right back with a nine-play, 69-yard march as Warner picked apart the defense on 7-for-7 passing for 64 yards. Faulk scored on a 1-yard run.
The Rams strung together a 12-play, 68-yard drive, with Warner going 7-for-10 for 56 yards, to take a 13-10 lead at halftime on fullback Robert Holcombe's 1-yard run. Warner gained 11 yards on a quarterback draw on third-and-1 from the Seattle 36.
Wilkins kicked a pair of 48-yard field goals in the first half.
Jay Bellamy stepped in front of rookie Trung Canidate, intercepted a pass by Warner and returned it 84 yards for Seattle's first touchdown of the season and a 10-3 lead in the second quarter.
Heppner kicked his first NFL field goal, a 19-yarder on Seattle's first possession of the game.
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