Seoul Subway Line 6 is a line of the Seoul Metropolitan Subway. The route connects Eunpyeong-gu and Jungnang-gu in a U-shaped manner, running through Yongsan-gu and Seongbuk-gu. It does not cross the Han River. It is mainly used to connect to the northern outskirts of Seoul and to relieve the traffic on other lines.

The Seoul Metropolitan Subway is a metropolitan railway system consisting of 23 rapid transit, light metro, commuter rail and people mover lines located in northwest South Korea. The system serves most of the Seoul Metropolitan Area including the Incheon metropolis and satellite cities in Gyeonggi province. Some regional lines in the network stretch out beyond the Seoul Metropolitan Area to rural areas in northern Chungnam province and western Gangwon Province, that lie over 100 km (62 mi) away from the capital.