2017 K League Challenge

The 2017 K League Challenge was the fifth season of the K League 2, the second-highest division in the South Korean football league system. Champions and winners of the promotion playoffs could be promoted to the K League 1.

Team changes
Relegated from K League Classic
 * Suwon FC
 * Seongnam FC

Promoted to K League Classic
 * Daegu FC
 * Gangwon FC

Newly joined
 * Ansan Greeners

Withdrawn
 * Goyang Zaicro
 * Chungju Hummel

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.

Final
The promotion-relegation playoffs were held between the winners of the 2017 K League Challenge playoffs and the 11th-placed club of the 2017 K League Classic. The winner on aggregate score after both matches earned entry into the 2018 K League 1.

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''1–1 on aggregate. Sangju Sangmu won 5–4 on penalties and therefore both clubs remain in their respective leagues.''

Attendance
Attendants who entered with free ticket were not counted.

Awards
The 2016 K League Awards was held on 20 November 2017.

Main awards

 * Most Valuable Player: 🇧🇷 Marcão (Gyeongnam FC)
 * Top goalscorer: 🇧🇷 Marcão (Gyeongnam FC)
 * Top assist provider: 🇰🇷 Chang Hyuk-jin (Ansan Greeners)
 * Manager of the Year: 🇰🇷 Kim Jong-boo (Gyeongnam FC)