The 2020 K League 1 was the 38th season of the top division of professional football in South Korea, and the eighth season of the K League 1. Jeonbuk Hyundai Motors won their eighth title, becoming the most successful K League club which had the most titles.
The regular season was scheduled to begin on 29 February and to end on 4 October, but was postponed until 8 May due to the COVID-19 pandemic.
On 24 April 2020, the K League Federation confirmed that they would adopt a modified plan for the season, reducing the number of matchdays to 27 including five matchdays of each divided final league.
Sangju Sangmu and the lowest-placed team at the end of the season were relegated to the K League 2 for the 2021 season.
In this season, one additional spot for players from ASEAN countries was added regardless of the "3+1" foreign players rule.
Relegated to K League 2
Promoted from K League 2
The following twelve teams competed in the 2020 K League 1.
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.
Players in bold were registered during the mid-season transfer window.
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The league was divided into two groups, the top six and the bottom six, after the 22nd matchday.
The 2020 K League Awards was held on 5 November 2020.
Attendants who entered with free ticket are not counted.