The tattoo is a quote from the movie, and reads "it's a mystery".
Cabello decided to take the plunge during a night out in Los Angeles with her boyfriend, Shawn Mendes, who also added a new design to his collection of skin art.
West Hollywood tattoo artist Kane Navasard debuted the small inking of the letter "A" in script font behind Mendes' right ear, a tribute to his teenage sister Aaliyah in a post on Instagram.
"Little letter 'A' for the man @shawnmendes," Navasard captioned the black and white photograph.
The couple has yet to comment on its new tattoos, but Cabello previously indicated having a permanent inking wasn't for her.