She ended her post by emphasising that the 83-year-old "exuded a natural warmth that always made you feel comfortable in his company".
"My condolences to Patti and the family. Love and light, Olivia."
The actress accompanied the sweet words with a photo of herself, Bert, and his now-widow Patti from recent years, as well as a throwback newspaper article of herself and the showbiz icon from 1971, when she and Bert teamed up for the Freedom from Hunger Campaign concert.
Also in the post was a video from 1980 documenting Olivia's appearance on The Don Lane Show, during which the singer was nothing but smiles when she was surprised by Bert.
In the footage, Don asked Olivia: "Do you know we have John Travolta here tonight?"
Clearly in disbelief that her former Grease co-star would be making an appearance, Olivia remained sceptical as the host requested "John" to come out.
At this point, Bert Newton dressed as Travolta sauntered into the studio before promptly dancing with Olivia, who was overjoyed at the sweet surprise (see above video).
The nostalgic post and kind words about Bert's legacy garnered a lot of comments from the singer's followers, as well as from Patti Newton herself.
"Thank you, my heart is broken xx," Patti wrote underneath Olivia's tribute.
"It's very, very devastating. All our hearts are breaking because he was just the most wonderful man," she told reporters.
"I left at ten past seven, and I was just pulling around to come into my drive and I get the call to say he'd taken his last breath at 7.22pm.
"So I missed him, but maybe he didn't want me to be there for his last breath."
As the nation continues to mourn his death, it has been confirmed that Bert will be farewelled with a state funeral.