| Competition: | KEB Hana Bank K League 1 |
| Season: | 2018 |
| Winners: | Jeonbuk Hyundai Motors (6th title) |
| Continentalcup1: | Champions League |
| Continentalcup1 Qualifiers: | Jeonbuk Hyundai Motors Gyeongnam FC Ulsan Hyundai Daegu FC |
| Relegated: | Jeonnam Dragons |
| Best Player: | Marcão |
| League Topscorer: | Marcão (26 goals) |
| Matches: | 228 |
| Total Goals: | 620 |
| Biggest Home Win: | Gangwon 7–0 Incheon (19 August 2018) |
| Biggest Away Win: | Gyeongnam 0–4 Jeonbuk (11 April 2018) Seoul 0–4 Jeonbuk (20 May 2018) |
| Highest Scoring: | Jeonnam 6–4 Suwon (19 August 2018) |
| Longest Wins: | 9 matches Jeonbuk Hyundai Motors |
| Longest Unbeaten: | 10 matches Jeonbuk Hyundai Motors |
| Longest Winless: | 14 matches Incheon United |
| Longest Losses: | 6 matches Daegu FC |
| Highest Attendance: | 30,122 Seoul 2–1 Suwon (5 May 2018) |
| Lowest Attendance: | 290 Sangju 0–1 Gangwon (24 November 2018) |
| Average Attendance: | 5,381 |
| Prevseason: | 2017 |
| Nextseason: | 2019 |
The 2018 K League 1 was the 36th season of the top division of professional football in South Korea since its establishment in 1983, and the sixth season of the K League 1, former K League Classic. The K League Classic was changed its name to "K League 1" in this season. As the 2018 FIFA World Cup start on 14 June, the last round before stoppage will be held on 19–20 May. The league will resume games on 7 July.
| Daegu FC | Gangwon FC | Gyeongnam FC | Incheon United | Jeju United | Jeonbuk Hyundai Motors | |
|---|---|---|---|---|---|---|
| Daegu Stadium | Chuncheon Songam Leports Town | Changwon Football Center | Incheon Football Stadium | Jeju World Cup Stadium | Jeonju World Cup Stadium | |
| Capacity: 66,422 | Capacity: 20,000 | Capacity: 20,245 | Capacity: 20,891 | Capacity: 35,657 | Capacity: 42,477 | |
| Jeonnam Dragons | Pohang Steelers | Sangju Sangmu | FC Seoul | Suwon Samsung Bluewings | Ulsan Hyundai | |
| Gwangyang Football Stadium | Pohang Steel Yard | Sangju Civic Stadium | Seoul World Cup Stadium | Suwon World Cup Stadium | Ulsan Munsu Football Stadium | |
| Capacity: 13,496 | Capacity: 17,443 | Capacity: 15,042 | Capacity: 66,704 | Capacity: 44,031 | Capacity: 44,102 | |
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 including a least one player from the AFC confederation. Players name in bold are registered during the mid-season transfer window.
Teams play each other twice, once at home, once away.
Teams play every other team once (either at home or away).
After 33 matches, the league splits into two sections of six teams each, with teams playing every other team in their section once (either at home or away). The exact matches are determined upon the league table at the time of the split.
The promotion-relegation play-offs were held between the winners of the 2018 K League 2 play-offs and the 11th-placed club of the 2018 K League 1. The winners on aggregate score after both matches earned entry into the 2019 K League 1.
-----FC Seoul won 4–2 on aggregate and therefore both clubs remain in their respective leagues.
| Rank | Player | Club | Goals | |
|---|---|---|---|---|
| 1 |  Marcão | Gyeongnam FC | 26 | |
| 2 |  Uroš Đerić | Gangwon FC | 24 | |
| 3 | Júnior Negrão | Ulsan Hyundai | 22 | |
| 4 |  Stefan Mugoša | Incheon United | 19 | |
| 5 |  Moon Seon-min | Incheon United | 14 | |
| 6 | Ricardo Lopes | Jeonbuk Hyundai Motors | align=center rowspan=3 | 13 |
| Dejan Damjanović | Suwon Samsung Bluewings | |||
| Lee Dong-gook | Jeonbuk Hyundai Motors | |||
| 9 | Kim Shin-wook | Jeonbuk Hyundai Motors | 11 | |
| 10 | Heo Yong-joon | Jeonnam Dragons | 9 |
| Rank | Player | Club | Assists | |
|---|---|---|---|---|
| 1 | Cesinha | Daegu FC | 11 | |
| 2 | Elías Aguilar | Incheon United | 10 | |
| 3 | Lee Yong | Jeonbuk Hyundai Motors | 9 | |
| 4 | Hong Chul | Sangju Sangmu Suwon Samsung Bluewings | 8 | |
| 5 | Han Seung-gyu | Ulsan Hyundai | align=center rowspan=2 | 7 |
| Negueba | Gyeongnam FC |
The 2018 K League Awards was held on 3 December 2018.
[2]| Month | Manager | Club | Division | |
|---|---|---|---|---|
| March | Jung Gab-suk | Bucheon FC 1995 | K League 2 | |
| April | Choi Kang-hee | Jeonbuk Hyundai Motors | K League 1 | |
| May | Nam Ki-il | Seongnam FC | K League 2 | |
| July | Kim Jong-boo | Gyeongnam FC | K League 1 | |
| August | Ko Jong-soo | Daejeon Citizen | K League 2 | |
| September | Ko Jong-soo | Daejeon Citizen | K League 2 | |
| October | Jo Sung-hwan | Jeju United | K League 1 |
Attendants who entered with free ticket are not counted.
