Tight end Eric Saubert made the game-winning two-point conversion for the Seahawks.
Seattle staged a stunning comeback to defeat the Los Angeles Rams in extra time, clinching their place in the NFL play-offs.
Overcoming a 30-14 deficit in the fourth quarter, the Seahawks triumphed 38-37 at home, notching their fifth straight victory.
While the Rams had already secured a playoff spot earlier on game day, the Seattle team booked their return to the play-offs after a 24-month absence.
With this outcome, the Seattle have taken over their Conference standings with a twelve and three mark, replacing the Los Angeles, who fell to the number five seed with an 11-4 record.
Quarterback Darnold had two picks but recovered to deliver two scoring throws, including the second TD to star receiver Jaxon Smith-Njigba in overtime.
The Rams held a 13-7 lead at the break before Kenneth Walker III broke free for a 55-yard scoring dash for the home side.
Rams cornerback Wallace then took back Darnold's initial pick for a big return, setting up a short score by Blake Corum on the ensuing snap.
In the fourth quarter, a scoring pass from Matthew Stafford to Puka Nacua pushed the advantage to 30-14, but Shaheed ignited the hope with a 58-yard return for a score.
Darnold then found AJ Barner in the end zone, and a successful conversion forced the contest into an extra period.
Although Nacua raced in for his second touchdown in OT, Smith-Njigba answered in kind to setup the decisive score.
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