| Competition: | K3 League Basic |
| Season: | 2018 |
| Winners: | Siheung Citizen (1st title) |
| Best Player: | Park Min-seon[1] |
| League Topscorer: | Bang Chan-joon (25 goals)[2] |
| Matches: | 110 |
| Total Goals: | 443 |
| Prevseason: | 2017 |
The 2018 K3 League Basic was the second season of the K3 League Basic. Yeoju Sejong and Chungju Citizen joined the league in this season. The top two teams were directly promoted to the K3 League Advanced, and third, fourth and fifth-placed team qualified for the promotion playoffs.
Relegated from K3 League Advanced
Promoted to K3 League Advanced
Newly joined
| Club | City | Stadium | Capacity | Manager | |
|---|---|---|---|---|---|
| Busan FC | Busan | Busan Asiad Supplementary Stadium | 15,000 |  Kim Jong-mun | |
| Buyeo FC | Buyeo | Buyeo Sports Complex | 6,000 | Kang Jeong-hoon | |
| Chungju Citizen | Chungju | Tangumdae Football Stadium | 600 | Gong Mun-bae | |
| Goyang Citizen | Goyang | Goyang Sports Complex | 41,311 | Kim Jin-ok | |
| Paju Citizen | Paju | Paju Stadium | 23,000 | Jeong Seong-hoon | |
| Pyeongchang FC | Pyeongchang | Pyeongchang Sports Complex | 6,000 | An Hong-min | |
| Siheung Citizen | Siheung | Jeongwang Sports Park | 200 |  Gléguer Zorzin | |
| Seoul United | Seoul | Nowon Madeul Stadium | 446 | Jo Dong-hyun | |
| Yangju Citizen | Pyeongtaek | Yangju Godeok Stadium | 15,000 | Kim Seong-il | |
| Yeoju Sejong | Yeoju | Yeoju Sports Complex | 21,600 | Oh Ju-po | |
| FC Uijeongbu | Uijeongbu | Uijeongbu Sports Complex | 28,000 | Kim Hee-tae |
When the match was finished as a draw, its winners were decided on the regular season rankings without extra time and the penalty shoot-out. Therefore, Chungju Citizen was promoted to the K3 League Advanced after the draw.[3]