The goals from the former Middlesbrough marksman put Jeonbuk seven points clear at the summit with eight games of the regular season remaining
Jeonbuk took the lead after 63 minutes in somewhat controversial circumstances. Shin Kwang-hoon was adjudged to have fouled Lee inside the area to give Jeonbuk a penalty and receive a second yellow card
Pohang were level in spectacular fashion just five minutes later as Noh Byung-joon fired a free-kick from 30 yards into the top corner.
Within 10 minutes Jeonbuk restored their lead as an innocuous looking shot from Lee wrong-footed the goalkeeper and bounced into the net.
Lee sealed the win just before the end, running onto a through ball from Seo Jung-jin and slotting home with a first time shot from near the penalty spot.
"The most important thing is that we won," the hat-trick hero told reporters after the game.
"It was a big game and we put on a good performance to get the three points but there is still a long way to go.
"It was a disappointing result for us," said Pohang coach Hwang Sun-hong.
"But we have to quickly put it out of our minds as we have some big games coming up starting with the FA Cup semi-final on Wednesday."
In the evening's other fixture, Busan I'Park drew 1-1 at Chunnam Dragons. Park Jung-woo put Busan ahead after 22 minutes but 10 minutes before the break, Kim Myung-joong equalised for Chunnam.
The point moves Busan into fourth place above Suwon on goal difference.