Cyrus, 17, and Hemsworth, 20, met on the set of "The Last Song" in 2009. The two have been denying breakup rumors for the past few months.
Miley took to her website in June to slam rumors that she and Liam had split.
"Just wanna clear up a rumor. Liam and I did not break up. EVER! We are so happy and a lot of that has to do with the amazing relationship he has with my family," she wrote.