According to animal-rights charity PETA, the star requested an all-vegan costume - including faux feathers and vegan leather - for the highly anticipated Charlie's Angels' theme tune.
'This is amazing'
"She's such an angel for animals!" PETA tweeted, attracting more than 1,000 likes.
"Yass. We don't live anymore in the stone age to wear an animal as [a] costume," one user commented - while another wrote: "WOAH this is amazing!"
Cyrus, who recently split with Celebrity actor Liam Hemsworth, is often vocal about veganism on social media.
Earlier this year, the musician posted a picture on her Instagram story to her [then] 82 million followers saying: "Today's tea: you can't say you care about animals if you eat them."
The Hannah Montana singer was also voted as one of the most influential vegans in 2017, and was offered the 'Celebrity Advocate Award' from The Animal Rights National Conference.
Event organizers praised Miley for having 'a strong voice for the animals' and said she 'not only talks the talk but walks the walk of the vegan lifestyle'.