“In a sunshine state of mind!” she captioned the gorgeous photo taken in Queensland.
The 55-year-old wore an ivory two-piece by Monday Swimwear, a brand owned by Tash Oakley, and teamed it with a matching robe.
Sonia’s 229,000 followers were in love with the snap, with many complimenting her on her ageless look and one even calling her the “most beautiful woman in Australia”.
“OMG! Do you actually age Ms. Kruger?” one person wrote.
“Eat your hearts out all you 20 something year olds,” another mused.
Sonia shared a similar sizzling swimsuit photo back in July to help promote her dance fitness program Strictly You.
“If Summer bodies are made in Winter we better hop to it,” she captioned the image, showing her wearing a white bikini top and a floral skirt.
Sonia launched the program in August last year after people kept asking her how she got her incredible figure.
On her Instagram she said she hoped to help people “Get fit, have fun and be your best and most fabulous self”.
“People were sort of saying to me 'What do you do? What do you eat? What workout do you do? How do you get your arms to look like that?" Sonia said in an interview with The Australian Women’s Weekly.
“Even now, if I post a picture on Instagram from The Voice I get so many questions from people about what I'm doing, what am I eating, what sort of workouts do you do, so it felt like a natural step to do this and to share it.”
“I knew that Seven were looking at bringing the show back and I actually thought if they change the format they should bring somebody new in to host it,” the screen veteran told TV Tonight in July.
She says when she got the call she was ‘sceptical’, not least about the show’s new, pre-recorded format.
“I was sceptical along with everybody else about the fact that it wasn’t going to be live and it was going to be pre-recorded,” she admitted. “How would the purists accept that?”
Big Brother was brought back this year, hitting screens in early June, after it was axed from rival network Channel 10 six years ago in 2014.