The first section from Jamsil to Moran opened in 1996, and the second section from Moran to Amsa was opened in July 1999.

In 2019, Line 8 had an annual ridership of 112 million or about 307,000 people per day.

[3] At 17.7 km (11.0 mi) in length, Line 8 is the shortest of all heavy rail Seoul Metropolitan Subway lines.

In 2014, construction was planned to begin in order to extend the line north of the Han River through Guri station to Byeollae station on the Gyeongchun Line in Namyangju-si, Gyeonggi-do; construction began in October 2015.

[7][8] The southern end is planned to be extended 3.9 km (2.4 mi) to Pangyo station.