The ex-Manchester United star was introduced midway through the second half and quickly made an impact, heading in a Moon Seon-min cross in the 73rd minute before adding a second goal five minutes later.
Jae-Moon Ryu and Cheon Seong-Hoon completed the comeback as the Dark Red Warriors secured a memorable victory.
FC Seoul had been on a three-game winless run and fell behind to goals from Kim Gun-Lee and Mo Jae-Hyeon before Lingard’s heroics turned the game around.
"To come back from 2-0 down and win 4-2 we showed amazing mentality, belief and resilience," Lingard posted on Instagram.
The win lifts Seoul to fourth in K League 1, though they remain some way behind leaders Jeonbuk. Next up, they face Daejeon Hana Citizen and will return to AFC Champions League action against Chengdu Rongcheng in November.