The duo posted a photo to Instagram over the weekend showing them enjoying the sunshine on Sydney Harbour.
The photo was accompanied by the statement “It’s time Australia… Marriage equality is a human right for all.”
Channing, who appeared on the cover of OUTinPerth for our Pride edition back in 2012, is a successful model who is also studying law.
Since revealing his sexuality in a groundbreaking interview with Michael Parkinson two years ago Thorpe has spoken out about marriage equality on several occasions.
The Say ‘I Do’ Down Under campaign was launched by Kylie Minogue and her fiance Joshua Sasse. High profile celebrities including Dolly Parton, Ellen DeGeneres, Jake Shears and Natalie Imbruglia have added their support to the campaign in recent weeks.