[1] Celtic preceded the 2018–19 campaign with a pre-season tour of Austria, with matches against SK Vorwärts Steyr, Bohemians 1905, Blau-Weiß Linz and Sparta Prague.

On 29 July, Celtic were drawn to face Partick Thistle at Firhill Stadium in the second round of the 2018–19 Scottish League Cup.

On 2 December, Celtic won the Scottish League Cup for the third consecutive season, defeating Aberdeen 1–0 in the final.

The Bhoys sealed their place in the final with James Forrest, Odsonne Édouard and Tom Rogic all on the scoresheet.

[17] The Bhoys won 3–0 in both legs – courtesy of goals from Odsonne Édouard, James Forrest, Callum McGregor and Moussa Dembélé – and secured a place in the next round.

[18][19] On 18 July, it was determined that Celtic would face Rosenborg (Norway) in the second qualifying round of the UEFA Champions League.

[21][22] On 1 August, it was determined that Celtic would face AEK Athens (Greece) in the third qualifying round of the UEFA Champions League.

[25] The Bhoys last faced the Lithuanian side in the 2002–03 UEFA Cup first round; a 10–1 aggregate victory marked the beginning of Celtic's path to the final in Seville.

[31] The kit range for the 2018–19 season is inspired by the Bold Bhoys and marks 115 years since the club first used green and white hoops on the jersey.