Receiver Saubert executed the decisive two-point play for the Seahawks.
Seattle engineered a stunning comeback to defeat the Rams in extra time, securing their spot in the NFL play-offs.
Overcoming a 30-14 hole in the fourth quarter, the Seahawks triumphed 38-37 at home, notching their fifth consecutive win.
While the Rams had become the first to earn a post-season berth earlier on Sunday, the Seahawks booked their return to the postseason after a two-year hiatus.
With this result, the Seahawks have taken over their division's race with a twelve and three mark, replacing the Rams, who fell to the number five playoff position with an eleven and four standing.
Signal-caller Darnold threw two picks but regrouped to make two touchdown passes, culminating in the second score to wideout Jaxon Smith-Njigba in overtime.
The visitors held a 13-7 advantage at the break before Walker broke free for a 55-yard touchdown run for the home side.
Rams defensive back Josh Wallace then returned Darnold's first pick for 56 yards, leading to a short score by Blake Corum on the next play.
In the final stanza, a scoring pass from Matthew Stafford to Puka Nacua pushed the Rams' lead to sixteen points, but Shaheed provided Seattle's comeback with a spectacular punt return.
Darnold then found Barner in the endzone, and a converted two-point play sent the game into overtime.
Although Puka Nacua scored for his second TD in overtime, Smith-Njigba answered in kind to set up the game-winning score.
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