William light-heartedly told Irwin and his dance partner Witney Carson that he was missing Irwin at the Earthshot awards but wished them the best of luck, stating they had a 'seriously good chance of winning it'.
Irwin had to miss the Earthshot awards ceremony in Rio de Janeiro due to his commitments with the popular dance competition.
Following the royal encouragement, Irwin and Carson achieved a perfect score for their Foxtrot performance.
Robert Irwin touchingly dedicated his perfect-scoring dance to his late father, wildlife conservationist Steve Irwin.