The couple married on America's Independence Day, July 4, in 1982 and their 26-year-old daughter decided to honour their special day yesterday.
Kelly took to her Twitter page to praise her parents for their happy union and posted a video featuring pictures of Sharon and Ozzy.
She wrote: 'Happy anniversary mum and dad! you are the definition of true love!'
Osbourne then posted a link to the video alongside with the words: 'This made me cry!'
However, the star did forget how many years they had been married and after initially writing, '30 years of true love!', she later corrected herself, 'Oops it's 29 years'.