The Australian duo, who shot to fame playing Charlene and Scott in Neighbours, duetted at London's O2 Arena on Friday (December 21).
Before the song's finale, Minogue asked the audience: "How long have you waiting for this for?"
'Especially For You' was a hit for the pair in 1988, selling over a million copies in the UK.
Minogue and Donovan reunited as part of Pete Waterman's Hit Factory Live Christmas Cracker concert, which was originally planned for Hyde Park on July 11 but had to be postponed due to bad weather.
Donovan also sang 'Nothing Can Divide Us' and 'When You Come Back To Me' solo.
Rick Astley, Steps and Bananarama also performed at the event, which was raising money for Cancer Research UK.
Watch Kylie and Jason reunite on stage below: