Seattle will now wait to see who they'll host next week as the Los Angeles Rams take on the Chicago Bears in the other NFC Divisional Round game.
It's the first time Seattle has reached the NFC Championship since the 2014 season, when they went on to lose the Super Bowl to the New England Patriots, a team still alive in these playoffs.
Running back Kenneth Walker III finished the game with 145 total yards and tied a single-game career high with three rushing touchdowns. Quarterback Sam Darnold, who was dealing with an oblique injury and didn't throw all week, finished the game completing 12-of-17 passes for 124 yards and one touchdown, earning his first-ever playoff win.
49ers star running back Christian McCaffrey was held to just 74 total yards (35 rushing on 11 carries). Brock Purdy finished with 177 total yards and two turnovers (one interception, one fumble).
Full game recap + highlights
First half
What better way to start a game than with a touchdown right off the kickoff?
Well, that's exactly what Rashid Shaheed did to put the Seahawks up 7-0 before the team even had their first offensive drive.
Shaheed became the only player in the NFL with a kickoff return and a punt return touchdown this season - totaling three combined on the season.
It was all Seahawks the rest of the way. After the touchdown, the Seahawks would force a turnover-on-downs during the Niners' first drive of the game.
As a result, they would take the ball 44 yards on 11 plays to set up a 31-yard field goal from Jason Myers.
On their next defensive possession, Seattle's Ernest Jones IV would strip the ball from 49ers' backup tight end Jake Tonges three plays later to get the ball back.
Seattle would take immediate advantage of the turnover, going 42 yards on five plays in less than three minutes to stretch the score to 17-0 before the end of the first quarter.
Darnold would find Jaxon Smith-Njigba for a four-yard touchdown pass.
San Fran would start show some life in the second quarter.
In both of their first two offensive drives, they would drive down the field in 10 plays, coming away with six total points thanks to a pair of Eddy Pineiro field goals, forcing the Seahawks to punt for the first time in the game in between.
But it wouldn't take long for the Seahawks to pour on the hurt.
After the second Niners field goal, Seattle would cap off a 10-play, 80-yard drive with a seven-yard Kenneth Walker III touchdown.
Second half
After forcing the 49ers to turn the ball over on downs for the second time on the night, and the first drive of the second half, Seattle would add another three points to the scoreboard, taking a 27-6 lead.
Jones IV, who forced a fumble earlier in the game, picked off Purdy on the following drive.
Seattle, as they did all night, would take advantage again and drive down the field to go up 34-6.
Walker III would score his second touchdown of the night with a 15-yard run this time around.
And, you may have guessed it, the Seahawks forced a third turnover-on-downs on the following 49ers offensive drive.
And, you may have guessed it again, Walker III would score yet again for the third time on the night to make it 41-6 with 12:43 left to go in the game.
Seattle would continue to bully the 49ers the rest of the night.
Purdy had yet another turnover after defensive end Demarcus Lawrence strip-sacked the young QB for his second turnover of the game and the third for the Niners as a team, costing their way to a win.