"This koala makes everything with me. We have built some unusual dreams together over many years," he wrote alongside the snap.
"Without her heart and brain, my dreams would remain just that. Thanks for building all the things with me little miss koala. I hope to build one more, as always, but as we know, it's not up to us."
The 41-year-old was recently crowned the winner of Dancing With The Stars.
He beat out hot favourite Courtney Act - the bookies choice - and couldn't believe the result himself, declaring: "I just want to say Courtney is the better dancer!"
Sam and partner Jorja Smith collected $50,000 for his chosen charity, Love Your Sister which supports those living with cancer.
The foundation was established by Sam's sister and former Secret Life of Us star, Connie, who died of breast cancer two years ago.
