The 26-year-old singer and actress shared "Slide Away" on Thursday after confirming her separation from Hemsworth last week.
Cyrus sings about change and letting go of a relationship in the new song.
"Once upon a time, it was made for us / Woke up one day, and it turned to dust / Baby, we were found, but now we're lost / So it's time to let it go," she sings.
Cyrus also references whiskey and pills and a house in the hills. Cyrus and Hemsworth lost their home in Malibu, Calif., during the California wildfires in 2018.
Cyrus confirmed her split from Hemsworth on Aug. 10 after more than 10 years together and less than a year of marriage.
"Liam and Miley have agreed to separate at this time," Cyrus' rep told People. "Ever-evolving, changing as partners and individuals, they have decided this is what's best while they both focus on themselves and careers."
Hemsworth wished Cyrus "nothing but health and happiness" in an Instagram post Monday.