The 32-year-old songstress led a group of cast of prominent women including actresses Penelope Keith and Angela Lansbury who become Dames and the star of the Oxo adverts, Lynda Bellingham who has also been awarded an OBE.
Click on the picture for full gallery of recipients.
Meanwhile, Gavin and Stacey comedy writer and actress Ruth Jones described her MBE as "proper tidy".
Katherine's honour is partly in recognition of her charity work. Aside from selling million of albums worldwide, the Neath-born soprano is also a supporter of the Macmillan nurses, who cared for her father when he was dying of cancer.
In March she ran the London marathon, raising £25,000 in his memory. Katherine has also been to Afghanistan to entertain soldiers serving in Camp Bastion.
Katherine said: "I am incredibly humbled to receive this great honour.
"To accept such an award after only a decade of service to music and charity, comes as a wonderful surprise.
"I share this award with the charitable bodies I am so privileged to work with, especially to those brave service men and women who risk so much for us all on a daily basis."
Good Life star Penelope Keith said it was "marvellous" to join the ranks of women she admires such as Judi Dench and Maggie Smith.
She added: "I found out six weeks ago but the way it works is they send you a letter and then you have to eat it and keep quiet on pain of death.
"I sort of feel elated, exhausted and thrilled. It's the big one ... I don't know what is better than the icing on the cake, but this is."
Lynda said her OBE was a boost because this year she has been battling cancer. "It has been a long and tough year but this award is just a fantastic way to move forward," she added. "I feel honoured and inspired and very grateful."