The two were married in a secret wedding ceremony in December.
"Liam and Miley have agreed to separate at this time. Ever-evolving, changing as partners and individuals, they have decided this is what's best while they both focus on themselves and careers," Cyrus' rep told Entertainment Tonight.
Her rep told People magazine that the couple will "still remain dedicated parents to all of their animals they share while lovingly taking this time apart."
Cyrus posted a photo Saturday with her wedding ring notably missing.