The 28-year-old star was pictured being driven away in an ambulance as she was rushed to a Los Angeles hospital, reported TMZ online.
Osbourne was busy filming her E! TV show 'Fashion Police' when she suddenly had a seizure that lasted 30 seconds.
However, the star is now recovering in hospital and tweeted her fans to let them know she was doing okay.
"Thank you all for your beautiful well wishes yes I did have a seizure they are just trying to figure out why?" she wrote alongside a photo of her tattooed arm, which was taped up with a drip.
A member of the audience was a doctor and attempted to help, and as soon as the star came round, her team insisted that she go to hospital.