Tight end Eric Saubert made the game-winning two-point play for Seattle.
Seattle engineered a remarkable fightback to overcome the Rams in overtime, clinching their spot in the postseason.
Rallying from a sixteen-point deficit in the final period, the Seattle squad triumphed by a single point at home, notching their fifth straight victory.
While the Rams had become the first to earn a post-season spot earlier on Sunday, the Seahawks booked their return to the play-offs after a 24-month absence.
With this result, the Seattle now lead their division's race with a 12-3 mark, replacing the Los Angeles, who dropped to the number five playoff position with an 11-4 standing.
Quarterback Sam Darnold had two picks but recovered to deliver two scoring throws, culminating in the second score to star receiver Jaxon Smith-Njigba in overtime.
The Rams held a six-point advantage at the break before Kenneth Walker III burst through for a 55-yard scoring dash for the home side.
Rams defensive back Josh Wallace then returned Darnold's first interception for a big return, setting up a one-yard touchdown by Blake Corum on the ensuing snap.
In the fourth quarter, a scoring pass from Matthew Stafford to Nacua pushed the Rams' lead to 30-14, but Rashid Shaheed provided Seattle's comeback with a 58-yard punt return.
Darnold then found Barner in the end zone, and a successful two-point play forced the contest into an extra period.
Although Puka Nacua scored for his second TD in OT, Smith-Njigba responded in kind to setup the decisive conversion.
Elena Vance is a digital strategist with over a decade of experience in UK business consulting, specializing in technology-driven growth solutions.