Receiver Eric Saubert executed the game-winning two-point play for Seattle.
The Seattle Seahawks staged a stunning fightback to defeat the Rams in extra time, clinching their place in the NFL play-offs.
Overcoming a sixteen-point hole in the final period, the Seahawks emerged victorious 38-37 at home, registering their fifth consecutive victory.
While the Rams had already secured a post-season berth earlier on Sunday, the Seahawks secured their place to the postseason after a two-year absence.
With this result, the Seahawks have taken over their Conference race with a 12-3 record, replacing the Rams, who dropped to the number five seed with an eleven and four record.
Signal-caller Darnold had two picks but recovered to deliver two scoring throws, including the second TD to wideout Jaxon Smith-Njigba in the extra period.
The Rams held a six-point lead at half-time before Kenneth Walker III broke free for a long touchdown run for the home side.
Los Angeles defensive back Josh Wallace then took back Darnold's initial interception for a big return, leading to a one-yard touchdown by Blake Corum on the next play.
In the fourth quarter, a scoring pass from Matthew Stafford to Puka Nacua extended the advantage to sixteen points, but Shaheed ignited Seattle's comeback with a 58-yard punt return.
Darnold then found Barner in the endzone, and a converted conversion forced the contest into overtime.
Although Puka Nacua scored for his another TD in overtime, Smith-Njigba answered in kind to setup the decisive conversion.