The decisive field goal was a 39-yarder and capped a game in which Akers set an NFL record with 42 field goals in a single season.
The 49ers (12-3) will earn a first-round bye in the playoffs should Atlanta defeat New Orleans Monday
Marshawn Lynch rushed for 107 yards and a touchdown on 21 carries for Seattle (7-8).
Tarvaris Jackson completed 15-of-28 passes for 163 yards with a TD toss to Doug Baldwin.
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