The singer, 46, made the surprise announcement on Instagram on Wednesday with her picture-perfect snaps from their big day at Cliveden House, in Taplow, Berkshire.
Ms Appleton and Mr Haines’ countryside wedding backdrop was gorgeous, decorated with dozens of floral displays.
The beautiful day could be seen in the glamorous black and white photographs shared on her Instagram on Wednesday.
The All Saints star shared the pictures with the words “I do” next to them.
Clivesden House is also where Meghan Markle spent the night before she married Prince Harry.
Newly-weds Mr and Mrs Haines have been swept up in a romance since November 2018 and now have vowed to spend the rest of their lives together.
Last year, the songstress dropped the bombshell she had given birth to her daughter Skipper.
The couple were delighted to welcome their baby girl after keeping her pregnancy a secret.
Also, the singer has a son Gene from her high-profile relationship with Liam Gallagher.
The exes were married in 2008 but their marriage broke down in 2013 and they were divorced by 2014.
In the past, the singer was once engaged to Robbie Williams.