The two men were carrying out routine maintenance when they were suffocated by a nitrogen leak in the room in which they worked.
In a statement LG said that four other workers were affected by the leak but their injuries were not life-threatening.
LG expressed regret over the incident and said it had begun an investigation.
In its statement, LG said the nitrogen leak occurred at a factory known as "P8" that is in Paju city north of Seoul, that makes LCD screens for large TV sets. The factory is believed to have the world's largest production line, making display panels for LCD and OLED TVs.
Nitrogen is used to wash the display panels during manufacturing.
LG said the accident was a ""terrible tragedy" and added that it was "working to uncover the exact sequence of events" that led to the deaths.
Two people have been killed during an accident at an LG factory in South Korea.