The Greek-born Australian coach will start his tenure with a Champions League second qualifying round first leg fixture against FC Midtjylland at Celtic Park.
Postecoglou’s men were drawn against the Danish side in Wednesday’s draw in Nyon, Switzerland, and confirmation of the exact dates for each leg has now been decided.
Celtic will host the first leg on Tuesday, July 20th at Celtic Park with a kick-off time of 7.45pm. The Scottish Premiership runners-up will then travel to Denmark the following week for the second leg on Wednesday, July 28th in the city of Herning with a UK start time of 7.45pm.
A club statement read: "Due to ongoing Covid-19 risk and restrictions, UEFA has decided not to allow any away supporters to attend any of the 2021/22 qualifying phase and play-off matches. Celtic Football Club is also asking supporters to continue following the government's COVID guidelines.”