The 16-year-old climate activist picked up the honor as part of PETA's Libby Awards ('Libby is short for 'liberation').
The awards 'recognize the most powerful young people advancing the pro-animal cause'.
Vegan for the animals and planet
According to the charity, Thunberg 'never misses an opportunity to address the link between animal agriculture and global climate change and to urge others to go vegan'.
Describing herself as vegan for 'ethical, environmental, and climate reasons', Thunberg has encouraged others - including her parents - to ditch or reduce animal products.
'She refuses to sit by and watch'
Whether she's leading a strike, gramming, or eating a meal, PETA salutes Greta Thunberg, who refuses to sit by and watch as the planet is destroyed and its animal citizens die for a fleeting taste of chicken nuggets or a slice of cheese," PETA Senior Director of Youth Programs, Marta Holmberg, said.
"PETA is recognizing Greta for speaking truth and inspiring passionate young activists to reject anything stolen from an animal."