Titled 'Saturday Night Glee-ver', the instalment will feature covers of 'Disco Inferno' by The Trammps, Bee Gees track 'Staying Alive' and other club classics.
According to the trailer, the episode will also feature a plot involving a sex tape of Brittany (Heather Morris) and Santana (Naya Rivera).
Glee showrunner Ryan Murphy said back in January that he was hoping to get Saturday Night Fever's John Travolta to appear.
A tribute episode to the late Whitney Houston, titled 'Dance With Somebody', will air the following week.
The Glee disco special airs next Tuesday (April 17) at 8/7c on Fox. UK viewers can see it Thursday, April 19 at 9pm on Sky1.