The film is based on the 1968 play by Mart Crowley, and follows a group of gay men who meet in New York to celebrate one of their birthdays. Everything is fun and games until the guests find themselves forced to confront some uncomfortable truths.
Parsons stars as a party planner in the show, alongside Matt Bomer, Zachary Quinto, Andrew Rannells, Charlie Carver, Brian Hutchison, Michael Benjamin Washington, Robin de Jesús and Tuc Watkins.
In one image, Parsons can be seen wearing a dressing gown and looking at himself in a mirror while Bomer stands shirtless behind him.
Another shows the cast dancing and laughing in the garden.
The role appears to be a big departure from The Big Bang Theory, in which Parsons played a physicist called Sheldon.
Parsons recently opened up about the "complicated" reason why he quit the sitcom after 12 seasons.
The Boys in the Band premieres globally on Netflix on 30 September.