Osbourne, 27, is co-host of "E! Fashion Police" and a former "Dancing with the Stars" contender.
"Long story short, I cracked my head open then kept passing out," Osbourne said via Twitter Sunday. "I have the all clear [and] my mum [Sharon Osbourne] came to get me."
UsMagazine.com said further details regarding the circumstances of Kelly Osbourne's injury are expected to be discussed on Sharon Osbourne's chat show "The Talk" Monday.