The 2008 AFC Champions League knockout stage was played from 17 September to 12 November 2008. A total of eight teams competed in the knockout stage to decide the champions of the 2008 AFC Champions League.
Qualified teams
The winners of each of the seven groups in the group stage qualified for the knockout stage. West Asia Zone had four teams qualified, East Asia Zone had three plus the title holders.
Match times were sorted chronologically by local time. The UTC figure given is for the time zone of the place in which the match was held (accounting for Daylight saving time in the areas in which it was in effect).