The Price Tag hitmaker was left fuming when her website was illegally accessed on Saturday (30Mar13), with jokers posting a rude note about her record label and the pop superstar in the news section.
The message, which has since been removed, read: "The whole Universal Republic (Universal Music) can suck Lady Gaga's d**k."
Jessie J has now issued an official apology to fans who were offended by the post.
In a message on her Twitter.com page, she writes, "Somebody has hacked my website...! How original! *Naaaat* (not) we are having it sorted Asap and my apologies for the rude message the hackers have left!"