Its branches and services cover a large part of the Seoul Metropolitan Area; totaling 218.3 km (135.6 mi) in route length.

Frequent service is provided between Soyosan, Dongducheon, Uijeongbu, Cheongnyangni, Seoul, Yongsan, and Guro, where trains split between Incheon in the west and Byeongjeom and Cheonan in the south.

Service to Yeoncheon is approximately once per hour, limited due to the single track section approaching Soyosan station.

Trains travel along Gyeongbu (Seoul-Cheonan), Gyeongin (Guro-Incheon), Janghang (Cheonan-Sinchang), and Gyeongwon (Hoegi-Yeoncheon) railway lines.

Korail operates a variety of express "rapid" (Korean: 급행 geup-haeng, Hanja: 急行) trains for long distance commuter services on Line 1.