The star has been part of the show since it started in 2012 along with co-host Reggie Yates, who has also revealed he has left the talent contest.
However, the two are not the first stars from the show to jump ship.
Judges Jessie J and Danny O'Donaghue have both announced since the end of the second series they will not be on the panel for the third.
After much consideration, I will not be returning for series 3 of The Voice UK. I've had two wonderful years on the show...
- Holly Willoughby (@hollywills) September 14, 2013
Meanwhile, Kylie Minogue has signed up to replace Jessie on the show.
Sad you won't see Holly on a Saturday night any time soon? Console yourself with our gallery of her gorgeous, glamorous style...