Select your origin and it will tell you how to get to COEX.

From Gangnam Express Bus Terminal      From Nambu Terminal
From East Seoul Bus Terminal    From Gangbuk (center of Seoul) area

Take the Subway Line #3 at the Gosok-Terminal (Express Bus Terminal) station, get off at Gyodae (Seoul National University of Education) station, and transfer to the Subway Line #2 in the direction towards Jamshil and get off at Samsung station. Use the Exit No. 5 or 6 connected to the COEX Mall (directly connected to ASEM Square, MegaBox and arcade on the lower lobby
level of COEX InterContinental Hotel)