Notable attendees included her sister Enya, her Clannad bandmates, U2 members Bono, The Edge, Adam Clayton and Larry Mullen Jr, Daniel O'Donnell and his wife Majella, and Andrea Corr. Ireland's President Catherine Connolly and Taoiseach Micheal Martin were represented at the service. The exact date of Brennan's death and the specific day of the funeral have not been confirmed.
Outside the church, a guard of honour was formed by local primary school pupils, a musical marching band, and staff from a community centre. The song 'Peacemakers' by Brennan, featuring the voice of her son Paul when he was four years old, played as the coffin entered. Symbols of her life brought to the altar included Brennan's harp, a lanyard from the last gig she played, and a Donegal GAA jersey. Musical performances during the service included contributions by Daniel O'Donnell and Brennan's siblings Ciaran and Pol. A recording of Brennan singing 'Perfect Time', which she performed in Rome in 2000 in front of Pope John Paul II and more than two million people, was also played. Parish priest Brian O Fearraig led the service, with attendance numbers and further details about her life and career during the service not disclosed.
According to Daily Mirror - 3am Showbiz, the parish priest described grace and grief standing side by side as memories were shared through tears of sadness and joy. He also noted that Brennan knew her gift was from God and used it faithfully, allowing her voice and harp to become instruments of beauty, peace, and blessing for the world. The cause of death beyond pulmonary fibrosis, such as potential complications, remains unknown.