Receiver Eric Saubert made the decisive two-point conversion for the Seahawks.
Seattle staged a stunning fightback to overcome the Rams in overtime, clinching their place in the postseason.
Overcoming a sixteen-point deficit in the final period, the Seahawks triumphed 38-37 at home, notching their fifth consecutive victory.
While the Los Angeles had become the first to earn a playoff spot earlier on Sunday, the Seahawks booked their return to the postseason after a 24-month absence.
With this outcome, the Seattle have taken over their division's standings with a twelve and three mark, supplanting the Los Angeles, who dropped to the number five seed with an 11-4 record.
Signal-caller Sam Darnold threw two interceptions but recovered to deliver two scoring throws, culminating in the tying TD to wideout Jaxon Smith-Njigba in the extra period.
The Rams held a six-point lead at half-time before Walker burst through for a 55-yard touchdown run for Seattle.
Los Angeles defensive back Josh Wallace then took back Darnold's initial pick for 56 yards, setting up a one-yard 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 30-14, but Rashid Shaheed ignited Seattle's hope with a spectacular punt return.
Darnold then found AJ Barner in the end zone, and a successful two-point play forced the contest into an extra period.
Although Nacua scored for his second TD in overtime, Jaxon Smith-Njigba answered in kind to setup the decisive score.
Elena is a tech enthusiast and freelance writer specializing in gadget reviews and digital trends.