Guests at the Earthshot Awards were encouraged to dress sustainably. Mayor Wu understood the assignment.

Boston Mayor Michelle Wu arrived at The Earthshot Prize Awards MGM Music Hall at Fenway.David L. Ryan/Globe Staff

The Earthshot Prize Awards are Friday evening, and Boston’s about to have its red carpet moment.

Or rather, its green carpet moment.

The star-studded event will honor the winners of this year’s prize and their innovative efforts to combat climate change. The glittery affair will take place at MGM Music Hall at Fenway and will feature performances by Billie Eilish, Annie Lenox, Chloe x Halle, and Ellie Goulding.

But as Boston readies itself for this moment on the global stage, fashion may be on the minds of many high-profile guests. The event boasts a special dress code — and it’s not traditional white tie.

Guests at the Earthshot Prize Awards are encouraged to “dress with sustainability front of mind,” according to an invitation for the event obtained by the Globe. Attendees should “avoid buying new clothing, if a new item is required, consider sourcing vintage, recycled, consignment, or sustainably produced clothes.”

This is an event focused on environmental innovation, activism, and leadership, after all.

Boston Mayor Michelle Wu has spent much time with the Prince and Princess of Wales during their visit to Boston. She’s also focused on the city’s climate resiliency efforts, spearheading a number of initiatives in her first year in office, including Boston’s new textile recycling program, energy-efficient electricity choice plan, and food composting program.

So for Friday’s Earthshot ceremony, Wu is ready to make a statement.

Boston Mayor Michelle Wu at The Earthshot Prize Awards MGM Music Hall at Fenway.David L. Ryan/Globe Staff

The mayor will be wearing a custom-made repurposed dress by designer Timothy Westbrook — who hasn’t worked with a single scrap of virgin clothing material in more than a decade.

“When I heard him say he’s ‘The Lorax of Fashion,’ I was ready to go,” Mayor Wu told The Globe, a reference to the beloved Dr. Seuss character who famously “speaks for the trees.”

Westbrook, 33, is the co-founder of the Brooklyn Sewing Academy in New York, and he designed a textile gown for the mayor that’s sourced from two different fine arts collections. Westbrook has woven audio cassette tape into the fabric, and the sash on the dress is repurposed from fallen umbrellas — a material Westbrook often works with.

“Mayor Wu is a classically trained pianist and violinist ... so knowing this, I made the garment with audio cassette tapes to express that part of the mayor,” he said.

Westbrook and Wu got connected through the mayor’s longtime hairstylist Jason Burke, co-owner of Powell & Burke Salon on Newbury Street. Burke, who’s designed some of the mayor’s looks in her first year in office, encouraged her to “level up” for the star-studded Earthshot ceremony, and brought in Westbrook.

“I was so humbled to be invited and get to come to Boston,” Westbrook said. “Mayor Wu is my Kate Middleton. She is my celebrity in all the things she does and stands for.”

The gown is made from 1970s rug yarns, and all the lining of the material is made from post-consumer scraps. Even the zipper is vintage.

“It’s been fun to work with a designer who has devoted his whole career to sustainable fashion, even way before it was fashionable to be talking about the environment and conservation,” Wu said.

Westbrook appeared on the fashion competition reality show “Project Runway” in 2013, and was dubbed the show’s sustainability-focused fiber artist.

“Hopefully Kate Middleton looks at Mayor Wu’s dress and says, ‘I need that gown,’” Westbrook said.