Nicole turned 35 on Friday (28 June) but it seems her fellow judges - Gary Barlow, Sharon Osbourne and Louis Walsh - waited until they got to Cardiff today to throw her a party.
After heading backstage, the former Pussycat Doll was pictured behind a large coffee table that had been covered in party hats, banners and streamers, not to mention her rather impressive cake.
An array of helium balloons also floated around the room and, in keeping with being in Wales, there was even a Welsh/English dictionary and an inflatable sheep propped up nearby!
Earlier this week, it was reported that Nicole had split with boyfriend Lewis Hamilton after five years. Although it has not been confirmed, Lewis' rep said he had "nothing to add" to the claims.
Whether she is still in a relationship or footloose and fancy free, Nicole was grinning from ear-to-ear, similar to when she arrived at the Cardiff auditions earlier in the day.