2021 K League 1
The 2021 K League 1, also known as the Hana 1Q K League 1 for sponsorship reasons, was the 39th season of the top division of professional football in South Korea, and the ninth season of the K League 1. Jeonbuk Hyundai Motors won their ninth title and fifth consecutive title.
After progressing 33 regular rounds, the league was divided into two groups, the top six and the bottom six, and each team played five matches against other teams in its group.
Teams
Team changes
Relegated to K League 2Promoted from K League 2
Locations
The following twelve clubs competed in the K League 1 during the 2021 season.| Team | City/Province | Abbreviation |
| Daegu FC | Daegu | Daegu |
| Gangwon FC | Gangwon | Gangwon |
| Gwangju FC | Gwangju | Gwangju |
| Incheon United | Incheon | Incheon |
| Jeju United | Jeju | Jeju |
| Jeonbuk Hyundai Motors | Jeonbuk | Jeonbuk |
| Pohang Steelers | Pohang | Pohang |
| Seongnam FC | Seongnam | Seongnam |
| FC Seoul | Seoul | Seoul |
| Suwon Samsung Bluewings | Suwon | Suwon |
| Suwon FC | Suwon | Suwon FC |
| Ulsan Hyundai | Ulsan | Ulsan |
Foreign players
Restricting the number of foreign players strictly to five per team, including a slot for a player from the Asian Football Confederation countries and a slot for a player from the Association of Southeast Asian Nations. A team could use five foreign players on the field each game, including at least one player from the AFC confederation. Samuel Pungi, who played for Pohang Steelers, was deemed to be a native player as he had been granted South Korean nationality.Players in bold were registered during the mid-season transfer window.
| Team | Player 1 | Player 2 | Player 3 | AFC player | ASEAN player | Former player |
| Daegu FC | ![]() Positions by matchdayResultsMatches 1–22Teams played each other twice, once at home, once away.Matches 23–33Teams played each other once, either at home or away.Matches 34–38Teams played each other once, either at home or away.Relegation play-offsThe promotion-relegation play-offs were contested between the winners of K League 2 play-offs and the eleventh-placed team in K League 1. ---- Gangwon FC won 4–2 on aggregate and therefore both clubs remain in their respective leagues. AwardsAnnual awardsThe 2021 K League Awards was held on 7 December 2021.
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