The actress-and-singer showed support for her mother Tish Cyrus, who has backed a campaign to stop carriage rides in 'The Big Apple', by pleading with her millions of Twitter followers to sign a petition to end the tourist attraction.
After the young starlet posted a link to the online petition more than 6,000 of her devoted fans signed up in just a few hours, helping organisers New Yorkers for Clean, Livable & Safe Streets exceed their goal of 100,000 signatures.
Miley excitedly tweeted: "You all made my mama and all the horses so happy :) my fans really do come in handy xx. (sic)"
Meanwhile, her mother Tish praised the 'Hannah Montana' star's "amazing" fans for supporting the cause.
She told E! News: "Miley grew up around animals and with all our horses growing up, so she is very passionate about protecting all animals.
"Miley's fans have been amazing. We were trying to reach at least 100,000 people signing the petition and, after Miley tweeted, her fans got us 6,000 signatures in a few hours and pushed us over. We couldn't have done it without all her fans."
Miley - who was raised in Nashville, Tennessee - and Tish join a host of other stars, including Alec Baldwin, Lea Michele and Pamela Anderson, who are behind the cause to eliminate horse-drawn carriage rides, deeming them abusive to the equine animals.