The 40-year-old singer-songwriter made a surprise appearance on the finale of the long-running CBS show on Wednesday night, crashing the Reunion Special to honor her favorite contestant, Tai Trang. Trang, 51, was a fan favorite all throughout season 32 -- which was set in Cambodia -- partly due to his love for animals and all living things, for example, saving a chicken he named Mark from being eaten.
Sia at first called out to host Jeff Probst from the audience, who then brought her up on stage for the huge surprise.
"I could not let Tai go home without saying that your, like, authenticity and your care for animals really inspired me," Sia told Trang, who made it to the final three but ultimately lost to 24-year-old New Jersey native Michele Fitzgerald. "And so I want to donate $50,000 to you, and I want to donate $50,000 to your choice of animal charity."
"And I just want to say thank you for showing America how to be kind to animals," she added, as the audience gave Trang a standing ovation.
Trang, a gardener from San Francisco, was visibly shocked at the "Chandelier" singer's generous offering, and took the moment to raise more awareness for animals.
"I really thank you so much for bringing awareness of animal… Not just animal, every living being and the planet alone," Trang said. "We cannot be so human-centric because without everything, the whole ecosystem, we will be doomed sooner than we think. We will be."
Last September, ET chatted with Probst, who joked that Survivor is actually better at finding love than The Bachelor.
"I mean Survivor, the first marriage we had was during a live finale," he explained. "Since then, I think we've had probably another half dozen couples who've married. Some of them have kids."
" ... You're living in extreme conditions with somebody," he continued. "You actually do begin to bond on a real human level. So it doesn't surprise me that you might find yourself connecting with somebody in that way."