It's all change for the classical singer, who has dyed her locks a darker shade of blonde and showed off the results in a picture posted to Twitter on Monday morning (20 January).
Katherine's new look came as she announced a brand new recording contract, adding the caption to her photo: "Going back to my roots... Musically! #NewRecordDeal #Announcement #Decca."
The mezzo-soprano confirmed this morning she has signed a three-album deal with Decca Records, the label that launched her career a decade ago.
Her next album will be released autumn 2014.
Katherine said: "It feels not only very exciting but very special to be returning to Decca – a decade after they first signed me and to many of the people who helped launch my career. It amazes me to think that this will be my 10th album and for this, it seems the perfect place to be going 'home' to."
The 33-year-old told BBC News that she was returning to her roots musically and if people had enjoyed her first few albums they would certainly like her upcoming effort.
Katherine was made an OBE in the New Year Honours list for services to music and charity.
Throughout her career she has sold millions of records worldwide and raised money for charities including Macmillan Cancer Support during last year's London Marathon, which she ran in honour of her late father, who passed away from the disease.