Cyrus confirmed earlier this week that she and Hemsworth, who have been together for three years, are planning to get married.
After the news broke, Cyrus took to her Twitter page to express her happiness.
"Thank you for all the love today," she wrote. "I'm happy to share this news with you all. I feel like all my dreams are coming true. Have a great day."
Cyrus also revealed that she was "so happy" that "Miley Hemsworth" was trending on the social networking site and thanked stars Rita Wilson and Jordin Sparks for their well wishes.
Meanwhile, the LOL star's father Billy Ray Cyrus also celebrated the engagement on Twitter, posting: "All I ever hoped for as a Daddy was to see my kids reach their dreams. To find happiness... peace of mind... and someday know... true love."
Watch a trailer for Miley Cyrus's movie LOL below: