The 26-year-old took to Instagram where he shared a photo of the rainbow flag with the caption, " Australia, your vote is super important, please vote yes. Love is love x".
The 'Perfect' singer, who was recently forced to cancel part of his world tour, donned the rainbow flag during his performance at the Glastonbury music festival this year.
Sheeran isn't the only A-lister who has shown his support in the Australian same-sex marriage vote
Liam Hemsworth shared an emotional message on Instagram about the vote last month.
"To all the Australians that care about equality and human rights please say YES to same sex marriage. Let’s not be silly about this. Vote YES for same sex marriage in Australia," he wrote.