Former Attorney General Máire Whelan is now a judge of the Court of Criminal Appeal.
Judge Whelan was formally appointed in a short ceremony at Aras an Uachtarán in the past half hour - despite numerous objections to the move.
Her warrant of appointment was signed by President Higgins and countersigned by An Taoiseach.
Two judges of the High Court - Eileen Creedon and Charles Meenan - have also been appointed at the ceremony.
There's been ongoing political upheaval over Maire Whelan's nomination but the Government maintains the decision is entirely legal.
File image: Máire Wheland and President Michael D. Higgins pictured at Aras an Uachtarán 10/02/15. Photo: Mark Stedman/RollingNews.ie