The bisexual star of Drive Angry is believed to have been single for several months after secretly ending her relationship with Tasya van Ree, who she began dating in 2008.
"They are no longer in a relationship," a source told In Touch, adding: "[Tasya] was [since seen] chatting and laughing with several beautiful women."
Heard has been romantically linked to Depp following his separation from girlfriend of 14 years Vanessa Paradis earlier this month.
The pair are believed to have got close while working together on The Rum Diary and reports emerged recently that Depp tried to woo her with a horse.
The Pirates of the Caribbean actor could end up paying close to £100m ($156m) to Paradis.