# 2021 K3 League

The 2021 K3 League was the second season of the K3 League as a semi-professional league. The 15 participating teams played each other twice, and the bottom team was relegated to the K4 League.

## Teams
### Team changes

Relegated to K4 League
* Chuncheon Citizen
* Jeonju Citizen
Promoted from K4 League
* Paju Citizen
* Ulsan Citizen
Withdrawn
* Gyeongju Citizen

### Stadiums and locations

| Club | City | Stadium | Capacity |
| Busan Transportation Corporation | Busan | Busan Gudeok Stadium | 24,363 |
| Changwon City | Changwon | Changwon Football Center | 15,116 |
| Cheonan City | Cheonan | Cheonan Football Center | 15,500 |
| Cheongju FC | Cheongju | Cheongju Stadium | 17,264 |
| Daejeon Korail | Daejeon | Daejeon Hanbat Sports Complex | 17,371 |
| Gangneung City | Gangneung | Gangneung Stadium | 33,000 |
| Gimhae FC | Gimhae | Gimhae Public Stadium | 25,000 |
| Gimpo FC | Gimpo | Gimpo Stadium | 1,024 |
| Gyeongju KHNP | Gyeongju | Gyeongju Civic Stadium | 12,199 |
| Hwaseong FC | Hwaseong | Hwaseong Stadium | 35,270 |
| FC Mokpo | Mokpo | Mokpo International Football Center | 5,952 |
| Paju Citizen | Paju | Paju Public Stadium | 23,000 |
| Pyeongtaek Citizen | Pyeongtaek | Sosabeol Reports Town | 15,000 |
| Ulsan Citizen | Ulsan | Ulsan Stadium | 19,471 |
| Yangju Citizen | Yangju | Godeok Artificial Turf Ground | 5,000 |

### Foreign players

| Club | Player 1 | Player 2 | Player 3 |
| Changwon City | Takuma Ishibashi | | |
| Cheonan City | Jerry van Ewijk | | |
| Cheongju FC | Muhammad Iqbal | | |
| Gimhae FC | Rafael Ramazotti | Lucas Willian | Luan Costa |
| Gimpo Citizen | Ayumu Tachibana | | |
| Pyeongtaek Citizen | Abdoulie Gomez | | |
| Ulsan Citizen | Martin Sawi | Paul Puk Kun Pal | |

## League table

| Pos | Team | Pld | W | D | L | GF | GA | GD | Pts | Qualification or relegation |
| 1 | Cheonan City | 28 | 16 | 6 | 6 | 50 | 25 | +25 | 54 | Qualification for Championship final |
| 2 | Gimpo FC (C, P) | 28 | 14 | 10 | 4 | 35 | 20 | +15 | 52 | Qualification for Championship semi-final and K League 2 |
| 3 | Mokpo City | 28 | 14 | 8 | 6 | 34 | 23 | +11 | 50 | Qualification for Championship first round |
| 4 | Gyeongju KHNP | 28 | 13 | 7 | 8 | 39 | 30 | +9 | 46 | Qualification for Championship first round |
| 5 | Gimhae FC | 28 | 12 | 8 | 8 | 39 | 35 | +4 | 44 | |
| 6 | Busan Transportation Corporation | 28 | 11 | 8 | 9 | 32 | 33 | −1 | 41 | |
| 7 | Ulsan Citizen | 28 | 9 | 11 | 8 | 32 | 24 | +8 | 38 | |
| 8 | Changwon City | 28 | 9 | 11 | 8 | 28 | 27 | +1 | 38 | |
| 9 | Daejeon Korail | 28 | 8 | 12 | 8 | 32 | 30 | +2 | 36 | |
| 10 | Paju Citizen | 28 | 8 | 11 | 9 | 32 | 36 | −4 | 35 | |
| 11 | Cheongju FC | 28 | 9 | 7 | 12 | 37 | 39 | −2 | 34 | |
| 12 | Hwaseong FC | 28 | 8 | 10 | 10 | 29 | 34 | −5 | 34 | |
| 13 | Gangneung City | 28 | 4 | 8 | 16 | 23 | 42 | −19 | 20 | |
| 14 | Yangju Citizen | 28 | 4 | 8 | 16 | 17 | 43 | −26 | 20 | |
| 15 | Pyeongtaek Citizen (R) | 28 | 5 | 7 | 16 | 20 | 38 | −18 | 2 | Relegation to K4 League |

## Results
### Matches 1–28

| Home \ Away | CHC | GIM | MOK | BTC | GYE | GIH | ULS | CHA | HWA | PCI | DKO | CHE | YJU | PTA | GNE |
| Cheonan City | — | 0–1 | 0–0 | 2–1 | 0–2 | 2–1 | 1–0 | 0–1 | 3–0 | 2–2 | 2–3 | 3–0 | 3–0 | 2–1 | 2–0 |
| Gimpo FC | 3–2 | — | 2–1 | 1–2 | 1–0 | 1–2 | 2–2 | 2–2 | 1–0 | 3–1 | 1–1 | 2–0 | 2–0 | 3–0 | 0–0 |
| FC Mokpo | 2–1 | 1–1 | — | 2–0 | 1–1 | 0–0 | 3–2 | 1–1 | 1–0 | 0–1 | 1–0 | 1–2 | 2–0 | 2–0 | 0–0 |
| Busan Transportation Corporation | 2–2 | 0–0 | 2–0 | — | 1–3 | 2–1 | 1–1 | 1–1 | 1–1 | 1–2 | 0–1 | 1–1 | 2–1 | 1–0 | 2–1 |
| Gyeongju KHNP | 0–2 | 0–0 | 2–0 | 1–0 | — | 2–0 | 2–2 | 0–2 | 1–0 | 4–2 | 1–1 | 1–2 | 1–0 | 3–2 | 1–1 |
| Gimhae FC | 1–5 | 1–1 | 0–1 | 1–1 | 3–1 | — | 1–0 | 1–0 | 1–1 | 0–1 | 3–3 | 1–0 | 3–0 | 3–1 | 5–2 |
| Ulsan Citizen | 1–2 | 0–1 | 1–0 | 0–1 | 1–1 | 0–0 | — | 2–0 | 1–1 | 4–1 | 1–1 | 0–0 | 2–0 | 1–0 | 4–0 |
| Changwon City | 1–1 | 2–3 | 1–3 | 1–0 | 0–0 | 1–2 | 1–0 | — | 2–2 | 1–1 | 3–1 | 0–1 | 0–1 | 0–0 | 1–0 |
| Hwaseong FC | 0–3 | 0–1 | 2–3 | 1–2 | 2–3 | 1–0 | 1–0 | 0–0 | — | 1–1 | 1–0 | 1–0 | 3–2 | 1–0 | 1–0 |
| Paju Citizen | 0–1 | 0–1 | 0–1 | 2–0 | 2–1 | 1–2 | 0–0 | 0–1 | 1–1 | — | 0–0 | 2–2 | 0–3 | 2–1 | 2–1 |
| Daejeon Korail | 1–1 | 2–0 | 0–1 | 5–1 | 1–3 | 0–0 | 1–1 | 0–2 | 2–0 | 2–2 | — | 1–0 | 0–0 | 0–0 | 1–0 |
| Cheongju FC | 0–2 | 0–0 | 1–2 | 1–3 | 1–2 | 3–0 | 2–2 | 3–0 | 3–3 | 0–2 | 1–3 | — | 2–0 | 0–3 | 2–1 |
| Yangju Citizen | 0–0 | 0–0 | 2–1 | 1–1 | 0–2 | 1–2 | 0–1 | 1–1 | 0–3 | 1–1 | 3–1 | 0–6 | — | 0–1 | 1–1 |
| Pyeongtaek Citizen | 1–4 | 1–0 | 0–2 | 0–2 | 1–0 | 2–3 | 0–1 | 1–1 | 1–1 | 0–2 | 0–0 | 2–2 | 0–0 | — | 2–1 |
| Gangneung City | 1–2 | 0–2 | 1–1 | 0–1 | 2–1 | 2–2 | 1–2 | 0–2 | 1–1 | 1–1 | 2–1 | 1–2 | 2–0 | 1–0 | — |

## Championship play-offs

When the first round and semi-final matches were finished as draws, their winners were decided on the regular season rankings without extra time and the penalty shoot-out.

### Bracket

| First round | First round | First round | Semi-final | Semi-final | Semi-final | Final | Final | Final | Final | Final |
| | | | 2 | Gimpo FC | 2 | | | | | |
| | | | 3 | Mokpo City | 0 | | | | | |
| 3 | Mokpo City | 1 | 3 | Mokpo City | 0 | | | | | |
| 4 | Gyeongju KHNP | 1 | | | | | | | | |
| 4 | Gyeongju KHNP | 1 | | | | | Gimpo FC | 1 | 2 | 3 |
| | | | | | | 1 | Cheonan City | 0 | 2 | 2 |

### Final

Gimpo FC won 3–2 on aggregate.