The 2005 K League Championship was the ninth competition of the K League Championship, and was held to decide the 23rd champions of the K League. After the regular season was finished, the first stage winners, the second stage winners, and the top two clubs in the overall table qualified for the championship. Each semi-final was played as a single match, and the final consisted of two matches.

Qualified teams

Bracket

Semi-finals

20 November 2005

Seongnam Ilhwa Chunma	1–2	Ulsan Hyundai Horang-i
Nam Ki-il 18'	Report	Lee Chun-soo 46' Lee Jin-ho 83'

Tancheon Sports Complex, Seongnam

Attendance: 12,427

Final

First leg

27 November 2005

14:30 KST

Incheon United	1–5	Ulsan Hyundai Horang-i
Radončić 89'	Report	Machado 13', 58' Lee Chun-soo 37', 46', 72'

Incheon Munhak Stadium, Incheon

Attendance: 35,356

Referee: Ko Keum-bok (South Korea)

Second leg

4 December 2005

14:00 KST

Ulsan Hyundai Horang-i	1–2	Incheon United
Choi Sung-kuk 18'	Report	Radončić 14', 26'

Ulsan Munsu Football Stadium, Ulsan

Attendance: 34,652

Referee: Lee Sang-yong (South Korea)

Ulsan Hyundai Horang-i won 6–3 on aggregate.

Final table