'He was left in a box Infront of Walmart. I don't understand how people can be so cruel. That's why we named him Happy,' wrote Miley.
And unsurprisingly, fans were eager to share their thoughts on the latest addition to the singer's family.
'Omg the cutest dog I have ever seen!!' commented one.
Miley's not the first star to rescue an animal - Selena Gomez ,19, and Justin Bieber, 18, decided to show their commitment to each other by taking in husky-mix Baylor earlier this year.