The couple announced their separation in May amid rumours of Ronan's alleged seven-month affair with a backing dancer.
Despite reports that the two had reconciled, the pair later issued a statement reaffirming the break-up of their marriage.
However, Ronan and Yvonne were pictured holding hands while walking on Bondi Beach this weekend.
Later, Ronan held his estranged wife's hand as she had a tattoo done at a shop in the resort, before they rode together on a Harley Davidson low-rider.
They also enjoyed lunch with their three children - Jack, 11, Missy, 9, and Ali, 5.