Receiver Eric Saubert made the decisive two-point play for Seattle.
Seattle engineered a stunning comeback to defeat the Rams in overtime, securing their spot in the postseason.
Rallying from 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 play-offs after a two-year absence.
With this outcome, the Seahawks now lead their division's standings with a 12-3 record, supplanting the Rams, who dropped to the fifth seed with an eleven and four standing.
Signal-caller Darnold had two picks but regrouped to deliver two touchdown passes, including the second score to wideout Jaxon Smith-Njigba in overtime.
The visitors held a six-point advantage at half-time before Walker broke free for a long touchdown run for Seattle.
Los Angeles defensive back Wallace then took back Darnold's first pick for a big return, leading to a one-yard touchdown by Corum on the ensuing snap.
In the fourth quarter, a touchdown from Matthew Stafford to Nacua extended the advantage to 30-14, but Rashid Shaheed ignited Seattle's hope with a spectacular return for a score.
Darnold then connected with Barner in the endzone, and a successful two-point play forced the contest into an extra period.
Although Puka Nacua raced in for his second TD in overtime, Smith-Njigba answered in kind to setup the game-winning score.
Elena Vance is a seasoned gaming journalist with over a decade of experience covering casino trends and industry developments across North America.