The 20-year-old posted a photo of the italic writing, which reads 'now I'm a warrior', on her Twitter account, adding the caption, "Thanks Bang Bang! Album release day!!! #DEMI (sic)"
It's been a busy week for Bang Bang as he also tattooed British model Cara Delevigne, inking a lion onto her index finger. His work was recommended to the British model by her best friend Rita Ora and Rihanna who have both gone under his needle.
Lovato has 12 other tattoos and admitted she regrets many of them and has even considered having laser treatment to remove them.
"I've thought about it before because, you know, when I get older I don't know if I want to have rock and roll on my middle finger. I'm young and I can rock it now and when I get older I can worry about it later.