The Oscar-winning singer is one of a number of stars urging people to say yes to same-sex marriage, and last month shared a post on Instagram about the vote, telling Australians: “You have a special special place in my heart.”
He has now offered to donate proceeds from the show ahead of the vote, the Sydney Morning Herald has reported.
Tickets for the show on January 16 went on sale on Monday morning, starting at $79.90 (£47.50). With a capacity of just under 2,000, it means the donation could reach the £30,000 mark.
Australian Marriage Equality co-chair Janine Middleton told the paper: “Sam knows all too well about the challenges faced by LGBTI Australians and his generosity towards them will help us achieve fairness and equality for all.
“Sam doesn’t need to do this, he isn’t Australian but he
understands what it feels like to be in a relationship that isn’t considered equal.
“Soon we hope to realise the equality he enjoys at home in the United Kingdom will soon be a reality here in Australia.”
Smith described Australia as a “home away from home” when he announced the gig earlier in October.
The Australian marriage equality vote closes on November 7, with the result due to be announced on November 15.