The 34-year-old British actress revealed plans to auction "one of the most extraordinary things I've ever worn" backstage at the awards ceremony, where she bagged the Golden Globes for best TV comedy or musical and best actress in a TV musical or comedy series for her BBC sitcom "Fleabag."
"The money that is raised from it will go towards relief in Australia," she said in a video shared online. "I think it's a beautiful idea from the team. I'm really excited to be part of that."
Waller-Bridge made a bold style statement at the Golden Globes in the plunging black and gold sequined trouser suit with lace detailing on the hems. She opted to wear it without a shirt.
The tuxedo was designed by Ralph & Russo, a London-based couture brand founded by Australians Tamara Ralph and Michael Russo.
Waller-Bridge is the latest celebrity to join relief efforts as wildfires continue to rage across Australia. The massive blazes have devastated wildlife, destroyed homes and left 24 people dead nationwide.
Married superstars Nicole Kidman and Keith Urban -- both native Australians -- have pledged $500,000 to wildfire efforts. Singer Pink has pledged the same. Several big names from the world of tennis, including Maria Sharapova and Novak Djokovic, have pledged donations.
On Sunday, Australian Prime Minister Scott Morrison cautioned that for some states, the most difficult fire seasons could be later in January and February. "The crisis is not over," he said. "There are months to go."