The limited edition Crimbo Juice is a spicier version of the original, with added ginger, clove and cinnamon.
Drag queens Frankie, 24 Carat Goldie and Myriam helped launch the new spiced ginger flavour, handing out bottles from a giant snow globe on Buchanan Street.
The famous orange and blue packaging has been changed to red and blue with a snowflake for the seasonal offering.
Mary Mac, aka 24 Carat Goldie, said: "Us Scots can't get enough of the ginger stuff and it's utterly fabulous helping to launch Irn-Bru Crimbo Juice.
"Spiced ginger is a real Christmas cracker."
Irn-Bru marketing director Adrian Troy said: "As our first limited edition flavour in over seven years, Irn-Bru Crimbo Juice combines the phenomenal taste of Irn-Bru that fans know and love with a taste of Christmas in every sip.
"The spiced ginger flavour means Irn-Bru lovers can really get into the festive spirit by enjoying mince pies washed down with a swig of Crimbo Juice."
The release follows the news that Barr's will also be launching a limited edition Irn-Bru 1901 this December, with this new/old version created using a recipe from a handwritten book stored deep in the company archives for over 100 years and described by the firm as “like nothing anyone has tasted before”.