According to the Herald Sun, the picture was 'liked' by the show's official Instagram account and was posted before station management became aware of it.
The post was swiftly deleted.
Herald Sun's Fiona Byrne in her Gossip Queen column asked readers: "Is posting a photo of your female co-host in her underwear, on her knees and apparently throwing up in a toilet really how KIIS FM Melbourne breakfast hosts Jase Hawkins and PJ Harding want to promote the launch of their new radio show?"
She went on the say: "Their show's tagline is 'always awkward'.
"If Friday's photo offering is any guide perhaps it should be changed to 'not funny'."
Sources told the News Corp publication the photo was indeed of PJ and that she was with Jase when he posted it online.
PJ also reportedly shared a unflattering image of her male co-host, but swiftly deleted it.
The radio stars had a history of posting embarrassing snaps of each other every Friday as part of their radio show in New Zealand.
Jase recently took to Instagram to reflect on his time in New Zealand before his show moves to Australian airwaves.
"Thanks NZ for the most incredible three years, I've loved every second of it. Time for the next adventure," he wrote.
PJ also wrote on Instagram: "Lots of laughs in 2017, here's to a s*** tonne more! Next stop: MELBOURNE (for good this time)."
- additional reporting Daily Mail Australia
