| Country: | South Korea |
| Season: | 2021 |
| Division1: | K League 1 |
| Champions1: | Jeonbuk Hyundai Motors |
| Division2: | K League 2 |
| Champions2: | Gimcheon Sangmu |
| Division3: | K3 League |
| Champions3: | Gimpo FC |
| Division4: | K4 League |
| Champions4: | Pocheon Citizen |
| Domestic: | Korean FA Cup |
| Dchampions: | Jeonnam Dragons |
| Wdivision1: | WK League |
| Wchampions1: | Incheon Hyundai Steel Red Angels |
| Prevseason: | 2020 |
| Nextseason: | 2022 |
| Flagicon: | yes |
This article shows a summary of the 2021 football season in South Korea.
See main article: South Korea national football team results (2020–present).
See main article: South Korea national under-23 football team results (2020–present).
See main article: South Korea women's national football team results.
See also: 2022 FIFA World Cup qualification – AFC second round.
See also: 2022 FIFA World Cup qualification – AFC third round.
See also: Football at the 2020 Summer Olympics – Men's tournament.
See also: 2022 AFC U-23 Asian Cup qualification.
See main article: 2021 K League 1.
See main article: 2021 K League 2.
See main article: 2021 K3 League.
See main article: 2021 K4 League.
When the match was finished as a draw, its winners were decided on the regular season rankings without extra time and penalty shoot-out.
See main article: 2021 WK League.
See main article: 2021 Korean FA Cup.
See also: 2020 FIFA Club World Cup.
| Team | Result | Round | Score | Opponent |
|---|---|---|---|---|
| Ulsan Hyundai | Sixth place | Quarter-finals | 1–2 |  UANL |
| Fifth place match | 1–3 |  Al-Duhail |
See main article: South Korean football clubs in the AFC Champions League.
| Team | Result | Round | Aggregate | Score | Opponent |
|---|---|---|---|---|---|
| Daegu FC | Round of 16 | Group I | Runners-up | 1–3 |  Kawasaki Frontale |
| 2–3 | |||||
| 7–0 | United City | ||||
| 4–0 | |||||
| 5–0 |  Beijing Guoan | ||||
| 3–0 | |||||
| Round of 16 | 2–4 | 2–4 | Nagoya Grampus | ||
| Jeonbuk Hyundai Motors | Quarter-finals | Group H | Winners | 2–1 |  Chiangrai United |
| 3–1 | |||||
| 2–2 | Gamba Osaka | ||||
| 2–1 | |||||
| 9–0 | Tampines Rovers | ||||
| 4–0 | |||||
| Round of 16 | 1–1 | 1–1 | BG Pathum United | ||
| Quarter-finals | 2–3 | 2–3 |  Ulsan Hyundai | ||
| Pohang Steelers | Runners-up | Group G | Runners-up | 2–0 | Ratchaburi Mitr Phol |
| 0–0 | |||||
| 0–3 | Nagoya Grampus | ||||
| 1–1 | |||||
| 4–1 | Johor Darul Ta'zim | ||||
| 2–0 | |||||
| Round of 16 | 1–0 | 1–0 | Cerezo Osaka | ||
| Quarter-finals | 3–0 | 3–0 | Nagoya Grampus | ||
| Semi-finals | 1–1 | 1–1 | Ulsan Hyundai | ||
| Final | 0–2 | 0–2 | Al-Hilal | ||
| Ulsan Hyundai | Semi-finals | Group F | Winners | 1–0 | Viettel |
| 3–0 | |||||
| 2–0 | BG Pathum United | ||||
| 2–0 | |||||
| 3–0 | Kaya–Iloilo | ||||
| 2–1 | |||||
| Round of 16 | 0–0 | 0–0 | Kawasaki Frontale | ||
| Quarter-finals | 3–2 | 3–2 | Jeonbuk Hyundai Motors | ||
| Semi-finals | 1–1 | 1–1 | Pohang Steelers |