"I really wish I could thank you ALL personally but I don't think I have enough years
left," she laughed.
"Thank you so much for your birthday wishes and I hope you are all well and staying safe! Love & light."
The performer was quickly met with a wave of support, including from fellow Aussie icon Kylie Minogue, who penned: "💞love you 💞."
Olivia recently sat down with New Idea to discuss what turning 73 meant to her, explaining that "age is a number" in her eyes.
“It’s how you feel inside, and I feel like I’m 33 – just much wiser! I guess when I was younger, I used to be focused on age a bit more, but life for me is wonderful so I have no complaints," the star said.
She went on to explain she feels very blessed to have made at this far, particularly considering "life can change in an instant".
WATCH: Olivia Newton-John watches Physical TikTok (Article continues after video)
"You can’t change the past and you can’t determine the future so the here and now is all you can focus on!" the 73-year-old said.
The Xanadu star was first diagnosed with breast cancer in 1992, then again in 2013, and later in 2017.
But even in the face of adversity, Olivia's zest for life and positive attitude never wavers.
“I truly believe it helps win over cancer or any challenge you are going through. Laughter also helps – I love laughing. Often at myself," the singer said.
