The Welsh warbler showcased the power of her vocal cords as she belted out Christmas carols in the comfort of her own home.
She wrote: "Rehearsing at home with Maestro Inglis for my concert at St David's Hall, Cardiff on 8th Dec & The Royal Albert Hall London on Dec 9th... Hope you can join us!"
Watch the video below to get a flavour of Katherine's talent - we're feeling festive/in the mood for a goblet of mulled wine.
As Louis Walsh would say: "That girl's got the X Factor".
Enjoy Katherine in picture format with the help of our gallery.