Receiver Saubert made the game-winning two-point play for Seattle.
Seattle staged a remarkable fightback to overcome the Rams in extra time, securing their spot in the postseason.
Rallying from a sixteen-point deficit in the final period, the Seahawks emerged victorious 38-37 at home, registering their fifth consecutive win.
While the Los Angeles had become the first to earn a playoff berth earlier on Sunday, the Seattle team secured their place to the postseason after a 24-month absence.
With this result, the Seattle now lead their division's standings with a twelve and three mark, supplanting the Los Angeles, who dropped to the fifth seed with an eleven and four standing.
Signal-caller Sam Darnold threw two picks but regrouped to make two scoring throws, including the tying TD to wideout Smith-Njigba in the extra period.
The visitors held a 13-7 lead at the break before Kenneth Walker III burst through for a 55-yard touchdown run for the home side.
Los Angeles defensive back Josh Wallace then returned Darnold's initial interception for 56 yards, setting up a one-yard score by Blake Corum on the ensuing snap.
In the final stanza, a scoring pass from Matthew Stafford to Nacua pushed the Rams' lead to 30-14, but Shaheed ignited the comeback with a spectacular punt return.
Darnold then connected with AJ Barner in the end zone, and a successful two-point play forced the contest into overtime.
Although Puka Nacua scored for his another TD in overtime, Smith-Njigba responded in kind to setup the decisive score.
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