The couple had been together over a decade.
In a statement released to Daily Star Online, a rep for Ant said: “In response to the recent speculation in the media, Ant is very sad to announce that, after 11 years, he is ending his marriage to Lisa McPartlin.
“Ant asks for privacy at this difficult time, for both himself, Lisa and their immediate families.
“No further statement will be made.”
A source added: “This was a tough decision for Ant but he has to do the right thing for his health.
“The marriage has effectively been struggling for eight months. He’s given it a good go.”
They added to The Sun on Sunday: “Ant’s big concern in the whole thing is Lisa and making it as easy as possible for her.”
Ant’s romance has been the talk of tabloids over the past few months ever since he entered rehab for an addiction to painkillers.
Due to his presenting role on ITV’s I’m A Celebrity… Get Me Out of Here Ant and Lisa spent November and December apart.
Lisa was unable to join the 42-year-old in Australia due to her job in London as a make-up artist on BBC hit Strictly Come Dancing.
While Lisa hasn’t directly commented on her relationship she sparked mass speculation when she tweeted a cartoon image of herself taking out a rubbish bag with ‘2017’ written on it.
The post was uploaded in the early hours of New Year’s Day.
Ant is reported to have welcomed in 2018 without Lisa, instead he went to Newcastle to be with his mum Christine and sister Sarah.