Tight end Saubert made the game-winning two-point conversion for the Seahawks.
Seattle staged a remarkable fightback to overcome the Rams in overtime, securing their place in the postseason.
Overcoming a 30-14 deficit in the fourth quarter, the Seattle squad triumphed 38-37 at home, notching their fifth straight win.
While the Rams had become the first to earn a post-season spot 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 division's race with a 12-3 mark, supplanting the Rams, who dropped to the number five playoff position with an eleven and four standing.
Signal-caller Darnold threw two interceptions but recovered to make two scoring throws, including the second score to star receiver Jaxon Smith-Njigba in the extra period.
The visitors held a six-point advantage at the break before Walker broke free for a 55-yard scoring dash for Seattle.
Los Angeles defensive back Josh Wallace then returned Darnold's initial pick for a big return, setting up a one-yard touchdown by Blake Corum on the ensuing snap.
In the final stanza, a scoring pass from Matthew Stafford to Nacua pushed the advantage to sixteen points, but Shaheed ignited the hope with a spectacular return for a score.
Darnold then connected with Barner in the end zone, and a converted conversion sent the contest into an extra period.
Although Puka Nacua raced in for his another touchdown in OT, Smith-Njigba answered in kind to set up the game-winning score.
Elias Vance is a Canadian journalist and political analyst with over a decade of experience covering national affairs and policy developments.