Although he put in a game effort, 40-year-old replacement Josh McCown struggled against a ferocious Seattle defence that finished the game with seven sacks.
Quarterback Russell Wilson produced another sound all-round performance as he threw for 325 yards and a touchdown while also rushing for 45 yards on the ground.
Rookie receiver DK Matcalf had a breakthrough game with 160 yards and the touchdown that effectively sealed the game in a powerful outing.
Seahawks running back Marshawn Lynch, who has come out of retirement to help the team deal with a big injury crisis, powered in for Seattle's other touchdown.
His 10th post-season rushing score put him eighth on all-time list.
The Seahawks head to Green Bay on on Sunday to take on the Packers in the NFC Divisional Round.
NFL play-off schedule/results bracket 2019/20
Wildcard weekend
Saturday January 4 (AFC)
Buffalo Bills (5) 19-22 Houston Texans (4) 9.35pm
Tennessee Titans (6) 20-13 New England Patriots (3) 1.15am (Sun)
Sunday January 5 (NFC)
Minnesota Vikings (6) 26-20 New Orleans Saints (3) 6.05pm
Seattle Seahawks (5) 17-9 Philadelphia Eagles (4) 9.40pm