Receiver Saubert executed the game-winning two-point conversion for the Seahawks.
Seattle engineered a remarkable fightback to overcome the Rams in extra time, securing their spot in the NFL play-offs.
Rallying from a sixteen-point deficit in the final period, the Seattle squad emerged victorious 38-37 at home, notching their fifth straight victory.
While the Los Angeles had already secured a playoff berth earlier on Sunday, the Seattle team booked their return to the play-offs after a 24-month absence.
With this outcome, the Seahawks have taken over their Conference race with a 12-3 record, replacing the Rams, who dropped to the fifth playoff position with an eleven and four record.
Signal-caller Darnold threw two interceptions but recovered to make two touchdown passes, including the tying TD to star receiver Smith-Njigba in overtime.
The visitors held a six-point lead at half-time before Walker burst through for a 55-yard scoring dash for the home side.
Rams defensive back Josh Wallace then took back Darnold's initial pick for 56 yards, setting up a one-yard score by Corum on the next play.
In the fourth quarter, a scoring pass from Stafford to Puka Nacua extended the advantage to 30-14, but Shaheed provided the comeback with a 58-yard return for a score.
Darnold then connected with AJ Barner in the endzone, and a successful conversion forced the game into an extra period.
Although Nacua scored for his another TD in overtime, Smith-Njigba answered in kind to set up the decisive score.