The line is operated by Central Japan Railway Company (JR Central) from Kameyama, the eastern terminus, to Shingū, and by West Japan Railway Company (JR West) from Shingū to Wakayamashi, the western terminus.

The segment between Shingū and Wakayama is nicknamed as the Kinokuni Line (きのくに線), after the alternate name of the Kii Province.

The Nanki limited express runs between Nagoya and Shingū or Kii-Katsuura with 4 return workings a day via the Ise Railway.

In 1935, the Kii-Katsuura to Taiji section was opened by JGR, extended to Kushimoto the following year, and to Esumi in 1940, providing a link to Wakayama and Osaka.

The successor to JGR, the Japanese National Railways (JNR), opened the Owase to Shingu section in stages between 1956 and 1959, completing the line.