The 2005 K League was the 23rd season of the K League. It kicked off on May 15, and was finished on 4 December. The format of the regular season and championship playoffs was the same as the one used in the 2004 season. Busan IPark won the first stage, and the second stage was won by Seongnam Ilhwa Chunma. Two winners were guaranteed their slot in the end-of-season playoffs. Incheon United and Ulsan Hyundai Horang-i also joined the playoffs according to the overall table after two stages. In the semi-finals Ulsan defeated Seongnam 2–1, and Incheon defeated Busan 2–0. The two victorious teams faced each other in the two-legged championship final. Ulsan won the first leg 5–1 at the Incheon stadium, and though Incheon won the second leg 2–1, Ulsan lifted their second league title 6–3 on aggregate.

Regular season

First stage

The first place team qualified for the championship playoffs.

Second stage

The first place team qualified for the championship playoffs.

Overall table

The top two teams in the overall table qualified for the championship playoffs.

Championship playoffs

Bracket

Final table

Top scorers

This list includes goals of the championship playoffs.

Awards

Main awards

Best XI

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