The star, who represented Australia with his band Voyager, announced to fans that he has been diagnosed with cancer.
In a poignant Instagram post, the 41-year-old revealed the band would be cancelling its upcoming tour to undergo “immediate treatment”.
He wrote: “Hi everyone, Danny here.
“Last week I was dealt some life-altering news: I’ve been diagnosed with cancer that requires immediate treatment.
“I am on strict doctors’ orders to not take this lightly, put my health first and get this sorted so we can be on stage again as soon as possible.”
Danny discussed the “extremely hard” decision to cancel the tour, telling fans the last show will take place in Fremantle, Western Australia on September 24.
He continued: “In the coming weeks I will focus on my health and family and ask that everyone please respect our privacy.
“I truly value and appreciate everyone’s support and understanding during this time.
“I’m surrounded by my incredible bandmates and team who are navigating all things Voyager whilst I am out of action.
“Love, your fierce friend Danny!”
Voyager’s European tour dates will be rescheduled to October 2024, with fans looking for a refund to contact their point of sale.
Voyager placed ninth in this year’s Eurovision final, just eight years after Australia first joined the annual celebration of music.
The band released their eighth album, entitled Fearless in Love, in July.
Presenter Rylan Clark, who hosted this year’s competition in Liverpool, sent warm words of encouragement to the musician.
“Dan we’re sending you all our love mate,” Clark tweeted.
The official Eurovision account added on Instagram: “Danny, you made so many friends in Liverpool – all of us are here for you, sending all our love.”