Receiver Saubert made the game-winning two-point conversion for Seattle.
Seattle staged a remarkable comeback to defeat the Rams in extra time, clinching their place in the NFL play-offs.
Rallying from a 30-14 deficit in the final period, the Seattle squad triumphed 38-37 at home, notching their fifth straight victory.
While the Los Angeles had already secured a playoff spot earlier on Sunday, the Seahawks booked their return to the postseason after a two-year absence.
With this outcome, the Seattle have taken over their division's race with a twelve and three record, replacing the Los Angeles, who fell to the number five seed with an eleven and four standing.
Signal-caller Sam Darnold had two picks but regrouped to deliver two touchdown passes, culminating in the second score to wideout Smith-Njigba in overtime.
The visitors held a 13-7 advantage at half-time before Kenneth Walker III broke free for a 55-yard scoring dash for Seattle.
Los Angeles cornerback Josh Wallace then returned Darnold's first interception for 56 yards, leading to a short touchdown by Blake Corum on the ensuing snap.
In the final stanza, a touchdown from Matthew Stafford to Nacua pushed the Rams' lead to sixteen points, but Shaheed provided Seattle's comeback with a 58-yard punt return.
Darnold then connected with Barner in the endzone, and a successful two-point play forced the contest into overtime.
Although Puka Nacua scored for his another touchdown in overtime, Smith-Njigba answered in kind to set up the decisive score.
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