Prince William and Kate Middleton Hit the Green Carpet in Style for 1st Annual Earthshot Prize Awards

The Duke and Duchess of Cambridge wore recycled formal wear for the occasion, which celebrated green activism.

Prince William and Duchess Kate Middleton were dressed to the nines for the inaugural Earthshot Prize Awards in London Sunday. Both the Duke and Duchess of Cambridge wore recycled formal wear for the occasion, which celebrated green activism.

William looked dapper in a green velvet blazer, which he paired with a black turtleneck and black trousers.

Meanwhile, Kate stunned in a flowing lilac gown by Alexander McQueen with a beaded belt. The Duchess wore her long locks down, pairing the look with diamond earrings.

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The mother-of-three first wore the dress, which met the event's dress code that requested guests wear environmentally conscious clothing, to the BAFTA Brits To Watch event in Los Angeles in 2011.

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William launched the Earthshot Prize earlier this year, under the leadership of the Royal Foundation, as part of his and Kate's ongoing environmental advocacy efforts. 

"These new solutions will work on every level, have a positive effect on environmental change and improve living standards globally, particularly for communities who are most at risk from climate change,” a description of the prize on the Royal Foundation's website read. “Prizes could be awarded to a wide range of individuals, teams or collaborations – scientists, activists, economists, community projects, leaders, governments, banks, businesses, cities and countries – anyone whose workable solutions make a substantial contribution to achieving the Earthshots."

This year’s Earthshot Prize will be chosen by a panel made up of the likes of Shakira and Cate Blanchett and featured performances from Ed Sheeran and Shawn Mendes as well as a performance by Coldplay, powered by the energy of 60 cyclists. Each recipient was be awarded £1 million to fund their innovative solutions for repairing the planet.

Prince Charles shared a sweet message of support to William ahead of the event on Twitter, expressing his overwhelming pride for his son's commitment to the environment.

"I am very proud of my son, William, for his growing commitment to the environment and the bold ambition of the Earthshot Prize. As a world, we need to come together to inspire, reimagine and build the sustainable future we so desperately need," Charles shared alongside a touching photo of the pair.

The inaugural Earthshot Prize Awards can be seen on BBC One, BBC iPlayer, and on Discovery's Facebook page.