The 'Edge of Glory' hitmaker was targeted by internet imposters, who accessed the email addresses and names of a number of the fans on her database.
However, no passwords or financial information was taken from the site.
A statement from Universal Music said: "The hacker took a content database dump and a section of email, first and last name records were accessed. There were no passwords taken and no financial information taken."
The record label has now contacted the people whose details were accessed and informed the police, Information Commissioner's Office and the British Phonographic Industry (BPI), which represents the music sector.
Just last week, Lady Gaga's YouTube account was shut down amid a copyright infringement claim from a Japanese TV channel.
The 25-year-old singer recently broke down in tears, saying she thinks people are "trying to destroy" her.
In a black and white YouTube video, she sobbed: "Sometimes I still feel like people are trying to destroy me ... I cannot be destroyed and I will not be destroyed. And you will never destroy the kingdom that is my fans."