1908–09 was Celtic's 21st season of football, in which they competed in the Scottish First Division.
Celtic also reached the final of the Scottish Cup against fellow Glasgow team Rangers.
Crowd disorder after it was announced that extra time was only provided in the event of a second replay caused serious damage at Hampden Park, as well as over 100 injured.
Both clubs requested the SFA not schedule a second replay and subsequently, the trophy and medals were withheld, with no winner ever declared.
Celtic also reached the finals of both the Glasgow Cup and the Glasgow Merchants' Charity Cup, but lost both: the Glasgow Cup to Third Lanark 4-0 after two replays; and the Charity Cup to Rangers, 4-2.