All types of high-speed, express, local, and freight trains provide frequent service along its entire length.

[1] Surveying began in 1896, and in spite of local protests, the Korean Empire gave Japan the right to build the line in 1898.

[2][1] Japan also sought to gain control of the Keigi Railway project that was to continue tracks further north, recognizing the trunk route as a means to keep Korea under its influence.

Following the Japanese invasion of Manchuria, from April 1, 1933, the line was traversed by direct trains from Busan to Andong (today Dandong) across the border.

[6] From December 1, 1936, the Akatsuki luxury express trains ran on the line with a maximum speed of 90 km/h (56 mph), and achieved the shortest pre-war travel time of 6 hours 30 minutes[4] in the timetable valid from November 1, 1940.

[8] The line remained the backbone of transport in South Korea after the war,[9] when diesel locomotives[6] and the cross-country Mugunghwa-ho train class was introduced.

[4] Following the 1961 coup, the Supreme Council for National Reconstruction started South Korea's first five-year plan, which included a construction program to complete the railway network, to foster economic growth.

[9] Korean National Railroad responded by introducing the Saemaul-ho class of elevated-comfort express trains on August 15, 1974.

[11][16] The Gyeongbu Line is the major route out of Seoul and Yongsan stations and, in addition to regular departures for Busan, trains travel along the Gyeongbu Line en route to Janghang, Gwangju, Mokpo, Suncheon, Yeosu, Pohang, Ulsan, Haeundae, Masan, and Jinju.

[19] However, the November 1, 2010, timetable change made Yeongdeungpo a KTX stop, for newly introduced trains that also use the Gyeongbu Line on the entire Seoul–Daejeon section, to serve Suwon.

Between Seoul and Cheonan, the Mugunghwa and Saemaul express trains on the Gyeongbu Line gave rail around a fifth of the modal share before the launch of KTX services.

Due to the short distance and the location of the KTX station outside the city, the conventional line could retain most of its passengers, and the increase in the total modal share of rail was modest.

[9] On the long-distance relations from Seoul to Daegu and Busan, the total share of rail increased from around two-fifths to a market dominating three-fifths, with the bulk of that traffic taken by the KTX.