"I'm surprised, humbled and completely overwhelmed," she said. "I just wish my little boy was here to share it with me."
Rosie, who beat an impressive field of nominees to the coveted title said she felt awkward at being recognised above "so many other amazing people."
"I am conscious that I have only been on my journey for just under twelve months, but I am determined to use the platform that this award affords me to hopefully make some really significant changes to the lives of women and children in Australia who are victims of family violence."
Rosie was named Australian of Year at a ceremony on the forecourt of Parliament House in Canberra. The Weekly's columnist, Jackie French, was named Senior Australian of The Year.
For the first time in the award's history, all four award categories went to women.
Rosie won 2015 Australian of the Year in a strong field of nominees similarly dominated by women, including adoption advocate, Deborra Lee Furness, neuroscientist Dr Lyn Beazley, London bombing survivor, Dr Gill Hicks and child safety campaigner, Hetty Jonhston.
The nation first met Rosie Batty last February in the most horrific of circumstances. Whilst she stood nearby, her 11 year-old son Luke was murdered by his father during cricket training in the tiny Mornington Peninsula township of Tyabb.
Though devastated by her loss, Rosie has nevertheless worked tirelessly since to campaign against domestic violence.
"I am deeply honoured to receive this award, and want to pay tribute to the amazing calibre of fellow nominees and the work they do," Rosie added. "But it's obviously a bittersweet moment for me. But that's a sadness I live with everyday."