The 42-year-old star is currently in Sydney, Australia where she was seen outside a cafe with the musician - who fronts band Lovebugs.
According to the Mail Online, Dannii and Adrian later headed to Bilgola Beach where they enjoyed the sunshine and sand with the brunette beauty's three-year-old son Ethan - who she had with sportsman Kris Smith.
Dannii is currently busy working on her latest record, and it is said she could be ready to sing about her break-up with Kris - who confirmed the end of their romance in April 2012 - and her rumoured fling with music mogul and 'X Factor' judge Simon Cowell.
An insider previously said: "The record will be very personal. Dannii wants to cover the events from the last couple of years.
"She's kept quiet about a lot of things and is using her music as an opportunity to finally speak about it all. She's actually finding it really therapeutic."