A representative for Ozzy and Sharon Osbourne's daughter has confirmed the news in a statement to Us Weekly magazine, revealing the couple has also split.
She says: "The split is amicable and the pair continue to have nothing but the utmost respect for one another.
"Kelly is looking forward to a new year full of fresh beginnings. No further comments will be provided by all parties (sic) and we request privacy, decorum and space from the press but don't expect it."
The couple met at Kate Moss' 2011 wedding - Mosshart's sister Alison is a bandmate of the British model's husband Jamie Hince.
Osbourne became engaged over New Year 12 months ago following a holiday proposal.
The 29 year old said: "I've never felt this close to another human being, ever... We just want to be together all the time."
She hinted that all was not well in her personal life in a tweet on 8 January which read: "It's all about perception. Sometimes the bad things that happen in life aren't really bad at all especially when you learn something from it!"
Osbourne was previously engaged to wed model Luke Worrall.