Dannii and partner Kris Smith took Ethan a short drive from their mansion to a nursing home in the city where it is thought they celebrated Ethan's big day with some of Dannii's elderly relatives.
The family spent two hours at the nursing home in the Surrey Hills area of the city before heading back to their AUD$1.5million property.
Dannii also posted a pic of a huge cupcake for Ethan with 'happy birthday' napkins on her Twitter page earlier today. (July 5)
She also wrote, 'Happy Birthday with a giant cupcake for Ethan.'
Dannii's celebrity friends, including Ethan's godfather, Irish crooner Brian McFadden and Aussie Bollywood star Tania Zaetta, visited the the Minogues on Saturday to kick off the birthday celebrations.
Kris also Tweeted earlier today 'threw his party on Saturday. He is loving it.'
A source close to Dannii in Australia has also reportedly denied reports the former X Factor judge has a female stalker.
Sydney's Daily Telegraph newspaper quotes the source saying, 'Dannii has no idea where this has come from.
'There's no truth to it.'