| Competition: | K3 League |
| Season: | 2015 |
| Dates: | 7 March – 21 November 2015 |
| Winners: | FC Pocheon (4th title) |
| Best Player: | Lee Sang-yong[1] |
| League Topscorer: | Park Dong-hee (30 goals) |
| Best Goalkeeper: | Choi An-seong |
| Matches: | 230 |
| Total Goals: | 961 |
| Prevseason: | 2014 |
| Nextseason: | 2016 |
The 2015 K3 League was the ninth season of amateur K3 League. The top three clubs of each group qualified for the championship playoffs after the home and away season of two groups (16 matches per team) and the interleague play (9 matches per team). The first-placed team in the overall table directly qualified for the final and the other group winners advanced to the semi-final. The interleague games had to have penalty shoot-outs when they were finished as draws, and 0.5 points were awarded for a penalty shootout defeat.
| Club | City | Stadium | Manager | |
|---|---|---|---|---|
| Cheonan FC | Cheonan | Cheonan Football Center |  Seo Won-sang | |
| Chungbuk Cheongju | Cheongju | Cheongju Stadium | Kim Jong-hyun | |
| Chuncheon FC | Chuncheon | Chuncheon Stadium | Kim Yong-ho | |
| Gimpo Citizen | Gimpo | Gimpo City Stadium | Yoo Jong-wan | |
| Goyang Citizen | Goyang | Goyang Eoulimnuri ground | Kim Jin-ok | |
| Gyeongju Citizen | Gyeongju | Gyeongju Civic Stadium | Kim Jin-hyung | |
| Hwaseong FC | Hwaseong | Hwaseong Stadium | Kim Jong-boo | |
| Icheon Citizen | Icheon | Icheon City Stadium | Lee Hyun-chang | |
| Jeonju FC | Jeonju | Jeonju University ground | Yang Young-cheol | |
| Jungnang Chorus Mustang | Seoul | Jungnang Public Ground | Yoo Bong-ki | |
| Paju Citizen | Paju | Paju Public Stadium | Oh Won-jae | |
| Pyeongchang FC | Pyeongchang | Pyeongchang Stadium | Hwang Young-woo | |
| FC Pocheon | Pocheon | Pocheon Stadium | In Chang-soo | |
| Seoul FC Martyrs | Seoul | Gangbuk Stadium | Kim Yong-hae | |
| Seoul United | Seoul | Madeul Stadium | Kim Chang-kyum | |
| Yangju Citizen | Yangju | Yangju Stadium | Lee Seung-hee | |
| Yeonggwang FC | Yeonggwang | Yeonggwang Sportium | Kim Han-bong | |
| FC Uijeongbu | Uijeongbu | Uijeongbu Stadium | Kim Hee-tae |
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