| Season: | 2018 |
| Manager: | Hwang Sun-hong (–30 April) Lee Eul-yong (30 April–) |
| League Result: | 11th |
| League Topscorer: | Go Yo-han (8 goals) |
| Season Topscorer: | Go Yo-han (9 goals) |
| Nextseason: | 2019 |
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The 2018 season was FC Seoul's 35th season in the K League 1.
| Type | Date | Opponents | Result | Score | Scorers | Notes |
|---|---|---|---|---|---|---|
| Practice matches during winter training spell in Murcia, Spain | 10 January 2018 |  R. Charleroi S.C. | 0–1 | |||
| 12 January 2018 | K.S.C. Lokeren Oost-Vlaanderen | 0–1 | ||||
| 16 January 2018 | Holstein Kiel | 2–1 |  Go Yo-han, Kim Sung-joon | |||
| 19 January 2018 |  FC Vaduz | 0–1 | ||||
| 26 January 2018 |  Yanbian Funde | 0–0 | ||||
| 30 January 2018 | FC Nordsjælland | 0–3 | ||||
| 2 February 2018 |  Dundalk | 0–1 | ||||
| 5 February 2018 |  Örebro SK | 1–0 | Park Chu-young | |||
| Practice matches during winter training spell in Kagoshima, Japan | 17 January 2018 |  Matsumoto Yamaga | 0–0 | |||
| 20 January 2018 | Tokai University | 7–0 | Go Yo-han, Jeong Hyeon-cheol, Park Chu-young Cho Young-wook, Lee Sang-ho, Kwak Tae-hwi |
See main article: 2018 K League 1.
See main article: 2018 Korean FA Cup.
Fixtures and Results at FC Seoul Official Website
| Position | Name | Notes |
|---|---|---|
| Manager | Hwang Sun-hong | |
| Assistant manager | Kang Chul | |
| First-team coach | Yoon Hee-joon | |
| Adilson dos Santos | ||
| First-team goalkeeping coach | Kim Il-jin | |
| Reserve Team Coach | Lee Eul-yong | |
| Reserve Team Goalkeeping Coach | Back Min-chul | |
| Fitness coach | Shin Sang-kyu | |
| U-18 Team Manager | Myong Jin-young | |
| U-18 Team Coach | Kim Jin-kyu | |
| U-18 Team Goalkeeping Coach | Weon Jong-teok | |
| U-18 Team Fitness Coach | Hwang Ji-hwan | |
| U-15 Team Manager | Kim Young-jin | |
| U-15 Team Coach | Park Hyuk-soon | |
| U-15 Team Goalkeeping Coach | Son Il-pyo | |
| U-15 Team Fitness Coach | Jung Hoon-gi | |
| U-12 Team Manager | Kim Byung-chae | |
| U-12 Team Coach | Seo Ki-man | |
| U-12 Team Goalkeeping Coach | Lee Ji-hun | |
| Chief scout | Kim Hyun-tae | |
| Scout | Lee Won-jun | |
| Jung Jae-yoon | ||
| Park Yong-ho | ||
| Position | Name | Notes |
|---|---|---|
| Caretake Manager | Lee Eul-yong | |
| First-team coach | Kim Seong-jae | May 2018~ |
| Park Yong-ho | May 2018~ | |
| Adilson dos Santos | ||
| First-team goalkeeping coach | Back Min-chul | May 2018~ |
| Reserve Team Coach | Yoon Hee-joon | May 2018~ |
| Reserve Team Goalkeeping Coach | Kim Il-jin | May 2018~ |
| Fitness coach | Shin Sang-kyu | |
| U-18 Team Manager | Myong Jin-young | |
| U-18 Team Coach | Kim Jin-kyu | |
| U-18 Team Goalkeeping Coach | Weon Jong-teok | |
| U-18 Team Fitness Coach | Hwang Ji-hwan | |
| U-15 Team Manager | Kim Young-jin | |
| U-15 Team Coach | Park Hyuk-soon | |
| U-15 Team Goalkeeping Coach | Son Il-pyo | |
| U-15 Team Fitness Coach | Jung Hoon-gi | |
| U-12 Team Manager | Kim Byung-chae | |
| U-12 Team Coach | Seo Ki-man | |
| U-12 Team Goalkeeping Coach | Lee Ji-hun | |
| Chief scout | Kim Hyun-tae | |
| Scout | Lee Won-jun | |
| Jung Jae-yoon | ||
| Position | Name | Notes |
|---|---|---|
| Manager | Choi Yong-soo | |
| First-team coach | Kim Seong-jae | |
| Yoon Hee-joon | ||
| Adilson dos Santos | ||
| First-team goalkeeping coach | Back Min-chul | |
| Reserve Team Coach | Park Yong-ho | |
| Reserve Team Goalkeeping Coach | Kim Il-jin | |
| Fitness coach | Shin Sang-kyu | |
| U-18 Team Manager | Myong Jin-young | |
| U-18 Team Coach | Kim Jin-kyu | |
| U-18 Team Goalkeeping Coach | Weon Jong-teok | |
| U-18 Team Fitness Coach | Hwang Ji-hwan | |
| U-15 Team Manager | Kim Young-jin | |
| U-15 Team Coach | Park Hyuk-soon | |
| U-15 Team Goalkeeping Coach | Son Il-pyo | |
| U-15 Team Fitness Coach | Jung Hoon-gi | |
| U-12 Team Manager | Kim Byung-chae | |
| U-12 Team Coach | Seo Ki-man | |
| U-12 Team Goalkeeping Coach | Lee Ji-hun | |
| Chief scout | Kim Hyun-tae | |
| Scout | Lee Won-jun | |
| Jung Jae-yoon | ||
All players registered for the 2018 season are listed.
| No. | Pos. | Nationality | Player | Notes | |
|---|---|---|---|---|---|
| South Korea | |||||
| South Korea | Hwang Hyun-soo | ||||
| South Korea | Lee Woong-hee (vice-captain) | ||||
| South Korea | Kim Dong-woo | ||||
| South Korea | Kim Sung-joon | ||||
| South Korea | Lee Sang-ho | ||||
| South Korea | Sin Jin-ho | ||||
| Brazil | Anderson Lopes | ||||
| South Korea | |||||
| Brazil | Evandro | ||||
| South Korea | Go Yo-han (captain) | ||||
| South Korea | Kim Han-gil | ||||
| South Korea | Kim Won-sik | ||||
| South Korea | Ha Dae-sung | ||||
| South Korea | |||||
| South Korea | Yun Suk-young | In | |||
| South Korea | Sim Sang-min | ||||
| South Korea | Park Jun-yeong | ||||
| South Korea | Yang Han-been | ||||
| South Korea | Yoon Seung-won | ||||
| South Korea | Lee Seok-hyun | Out | |||
| South Korea | |||||
| South Korea | Pak Min-gyu | ||||
| South Korea | Kim Nam-chun | Discharged | |||
| South Korea | Shin Seong-jae | ||||
| South Korea | Hwang Ki-wook | ||||
| South Korea | Park Hee-seong | ||||
| South Korea | Jeong Jin-wook | ||||
| South Korea | Son Moo-been | ||||
| South Korea | Cho Young-wook | ||||
| South Korea | Park Sung-min | ||||
| South Korea | Song Jin-hyung | ||||
| South Korea | Yoon Jong-gyu | ||||
| South Korea | Kim Won-gun | ||||
| South Korea | Yu Sang-hun | Discharged | |||
| South Korea | Kim Woo-hong | ||||
| South Korea | Park Dong-jin | ||||
| South Korea | |||||
| South Korea | Jung Won-jin | In | |||
| Croatia | Ivan Kovačec | Out | |||
| South Korea | Yun Ju-tae | Discharged | |||
| Serbia | In |
| No. | Pos. | Nationality | Player | Moving To | Loan Period | |
|---|---|---|---|---|---|---|
| South Korea | Yu Sang-hun | Sangju Sangmu | 2016/12–2018/09 | |||
| South Korea | Kim Nam-chun | Sangju Sangmu | 2016/12–2018/09 | |||
| South Korea | Yun Ju-tae | Sangju Sangmu | 2016/12–2018/09 | |||
| South Korea | Ko Kwang-min | Hwaseong FC | 2016/12–2018/09 | |||
| South Korea | Ju Se-jong | Asan Mugunghwa | 2018/01–2019/10 | |||
| South Korea | Lee Myung-joo | Asan Mugunghwa | 2018/01–2019/10 | |||
| South Korea | Lee Kyu-ro | FC Pocheon | 2018/01–2019/12 | |||
| South Korea | Kim Ju-yeong | FC Pocheon | 2018/01–2020/06 | |||
| Spain | Osmar | Cerezo Osaka | 2018/02–2019/01 |
Note: Where a player has not declared an international allegiance, nation is determined by place of birth.
※ In: Transferred from other teams in the middle of the season.
※ Out: Transferred to other teams in the middle of the season.
※ Discharged: Transferred from Sanjgu Sangmu or Ansan Mugunghwa for military service in the middle of the season (registered in 2019 season).
※ Conscripted: Transferred to Sangju Sangmu or Ansan Mugunghwa for military service after the end of the season.