2018 K League 2

The 2018 K League 2 was the sixth season of the K League 2, the second-highest division in the South Korean football league system.

Asan Mugunghwa once again grabbed an opportunity for promotion by winning its second K League 2 title (officially first title after Ansan era), but its owner Korean Police Agency did not recruit new players who could meet clubs' requisite for maintenance before the end of the season. Asan Mugunghwa, which was in the process of being dissolved, was finally disqualified from promoting.

Runners-up Seongnam FC directly qualified for the K League 1 instead of Asan Mugunghwa, and the third, fourth, and fifth-placed team advanced to the promotion playoffs.

Team changes
Relegated from K League Classic
 * Gwangju FC

Promoted to K League 1
 * Gyeongnam FC

Personnel and sponsoring
Note: Flags indicate national team as has been defined under FIFA eligibility rules. Players may hold more than one non-FIFA nationality.

Foreign players
Restricting the number of foreign players strictly to four per team, including a slot for a player from AFC countries. A team could use four foreign players on the field each game.

As of 24 July 2018.

Final
The promotion-relegation playoffs were held between the winners of the 2018 K League 2 playoffs and the 11th-placed club of the 2018 K League 1. The winners on aggregate score after both matches earned entry into the 2019 K League 1.

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FC Seoul won 4–2 on aggregate and therefore both clubs remain in their respective leagues.

Attendance
Attendants who entered with free ticket were not counted.