The pair have been seen together in recent weeks, more than three years after Schwarzenegger, 21, first voiced his affection for Cyrus.
The handsome, buzzed-about son of Arnold Schwarzenegger and Maria Shriver was speaking to Details about his dating prospects in May 2011 when he admitted, "My eye, though, is set on Miley." He was previously linked to the likes of Taylor Swift and his USC classmate Tootsie Burns.
After a brief fling in 2011, when Cyrus was on a break from then-boyfriend Liam Hemsworth, Schwarzenegger finally reconnected with his crush earlier this year. Insiders tell Us the stars have been quietly dating for "several months."
"They have been friends for a long time," a source tells Us. "They have a ton of common friends so they have run in the same circles for years." After splitting from Hemsworth in 2013, Cyrus dated producer Mike Will Made-It until earlier this year.
Cyrus and Schwarzenegger celebrated Halloween together at Hollywood's Roosevelt Hotel, says a second source, who adds that they went back to the "We Can't Stop" singer's house after the bash.
"She thinks he's hot, she thinks he's cool," a third source close to Cyrus told Us. "Patrick is a nice good guy. He's grown up in Hollywood just like her and it was only a matter of time before they hooked up."
The relationship is casual at this point, as sources tell Us "it's not serious," but Schwarzenegger is "seeing where it goes" and "he likes her."