Her charity Love Your Sister shared the devastating news on Facebook earlier tonight.
'We lost Connie today. Or, as she asked me to say, she died of cancer today. It was so beautiful. We laughed, we cried, we sang stupid songs from our childhood to her, which she loved (mostly!). I read her so many village messages, which she relished. She went so richly, and with such grace. Trust me, she was genuinely cushioned by your love, till the end,' the post read.
Samuel also shared a special tribute message to Connie on tonight's episode of The Project.
'She did so well. Please tell all our friends at The Project not to be sad for her. It was beautiful as such a thing could be and there were sh*tloads of rainbows in the final hours. See you soon,' he said.
Connie was first diagnosed with bone cancer aged 11 and then went on to discover a tumour in her womb at 22 and was diagnosed with breast cancer seven years ago.
Speaking to the Canberra Times, the mum-of-two said: 'So that's 10 to 11 years of cancer treatment in a 40-year lifespan and I guess my organs are just saying, "No more. No more".'
Samuel and Connie – who with just one year between them have been inseparable since childhood – co-founded the charity Love Your Sister, which aims to raise money and raise breast cancer awareness.
During her final days, Governor-General Sir Peter Cosgrove visited Connie’s bedside to award Medal of the Honour of Australia for all her hard work in helping breast cancer research.