The star of the Grammy-nominated Irish music group looked stunning in a pretty tea-length gown as she celebrated her nuptials with husband Anthony Byrne in Tinakilly Country House Hotel in Wicklow.
Messages of congratulations flooded in for the couple as groom Anthony, who plays bagpipes for the hugely successful group, shared a snap of the happy pair on Instagram.
Susan's big brother Brian took to Twitter to congratulate his little sister on her 'magical' day, sharing a photo of himself and their mother, who wore a beautiful pastel blue pleated dress and matching hat.
"Magical day at my beautiful sisters wedding. Me and mum," he wrote, tagging sister Susan and her new husband and adding a simple 'congrats'.
The popstar looked to be enjoying the celebrations as he took to the stage later in the night to entertain guests with his version of Mustang Sally.
In a video posted by a guest to Instagram, the former Westlife superstar is seen delivering a rocky rendition of the soulful tune which features in the Irish movie The Commitments.
Stage star Susan had a busy year in 2016, touring around the world with her all-female group. The group return to Ireland again in September this year, before jetting off to Japan for concerts in Tokyo and Osaka.
They are then scheduled to appear in Australia until October before travelling to the UK for a string of concerts up and down the country.
The hugely popular vocal and fiddle ensemble, consisting of vocalists Máiréad Carlin, Éabha McMahon, violinist Tara McNeill and Susan, has sold more than nine million records worldwide and made 11 albums.
Their album Destiny, released in January of 2016, was nominated for Best World Album in the Grammys last year.