In December 2008, 20, Billboard magazine named Celtic Thunder Top World Album Artist.Their first three albums also placed in the top 10 for World Albums.On 13 January 2014, after three years with Celtic Thunder, Emmet Cahill announced his decision to leave Celtic Thunder via his Facebook fan page.On 12 March 2014, Sharon Browne announced that George Donaldson, one of the five original Celtic Thunder principal singers since the Celtic Thunder auditions in August 2007, died of a heart attack.On 17 December 2008, Celtic Thunder completed their 2008 US tour of fifty cities.They also toured the United States extensively in fall 2009.On 16 December 2015, Colm Keegan announced that he will be taking a break from touring with Celtic Thunder for a year and will be recording a new solo album.Emmet Cahill rejoined Celtic Thunder to replace Keegan.
They are accompanied by the Celtic Concert Orchestra under the direction of Phil Coulter, the musical director of the group.
After Kelly returned, Keegan was asked to become a permanent member of the group.
On 15 October 2012, Celtic Thunder performed at The Pentagon.
The album was titled Celtic Thunder and the concert special was titled The Show.
It was filmed at The Helix in Dublin, Ireland, on 18 August 2007.