In 2010, the Boyzone star announced the couple were separating, but they were later said to have rekindled their relationship.
At the time they were able to move past rumours Ronan had been unfaithful with a backing dancer.
However, in separate Twitter announcements on Sunday, they told fans they were no longer together.
The singer tweeted: "Sadly our news is true. Thank u all for your support. Yvonne and I still love and care for each other and want to protect our kids. X"
Yvonne Keating wrote on her Twitter page: "Sadly, our marriage ended late last year. We kept this news private to give everybody involved time to adjust. Thank for your support x"
She later posted: "Overwhelming amount of support for myself and Ronan on twitter tonight... thank you for all your lovely messages. It means a lot xx"
Ronan and his Irish model wife have three children, 13-year-old Jack, Marie, 11, and Ali, six.