The 2018 KBO League season was the 37th season in the history of the KBO League.

Each team can sign up to three foreign players.

Due to the high proportion of pitchers signed in previous years, beginning in 2014 the league has mandated that at least one of the foreign players must be a position player.

The series started with a 1–0 advantage for the fourth-placed team.

Nexen Heroes (2) vs. KIA Tigers (0) Hanwha Eagles (1) vs. Nexen Heroes (3) SK Wyverns (3) vs. Nexen Heroes (2) Doosan Bears (2) vs. SK Wyverns (4)