The one-time '80s dream couple will be performing the duet as part of the PWL Hit Factory Live concert in London tomorrow, to commemorate the 25th anniversary of the PWL record label.
"Rehearsals with gorgeous @JDonOfficial [Jason Donovan] for @PWLHitFactory," the Aussie pop princess captioned, tweeting a picture of the two singers and their backing band at the rehearsal studio.
Kylie revealed she would be singing with her former boyfriend and Neighbours love interest last month.
"I'm going to sing 'Especially for You' with Jason Donovan," she told Glamour.
"I don't think we'll even need to sing it. I'm sure the audience all went through the Neighbours wedding. It's going to bring the house down."
The concert is being held in London's Hyde Park, and will feature performances from former label mates Bananarama, Rick Astley, 2 Unlimited and Dead or Alive.