We've been doing some digging and here are some of her favourite things - beauty-wise, of course...
1. Laura Mercier Secret Camouflage, £26
Like every celebrity known to man, Katy loves this Laura Mercier concealer. 'It covers spots without looking cakey,' she says.
2. L'Oréal Professionnel Série Expert Vitamino Colour Colour Protecting Gel-Masque, £12.80
Her hair has been coloured since she was 15, so Katy lives and dies by this stuff for protecting her hair and adding shine.
3. Nubar Nail Varnish in Red Sea Coral, £8
Katy constantly changes her nails to go with her different outfits and this gorge coral was a favourite at the MTV VMAs.
4. myface Blingtone Eyeshadow in Diamonds & Pearls, £12.99
She has a whole selection of myface cosmetics but particularly loves this silver, metallic shadow.
5. ghd Gold Classic Styler, £119
'I love ghd tools,' Katy says. 'ghds have a reputation of being the best in the biz, and I like being associated with that!'
6. Benefit Benetint, £24.50
Katy loves this lip and cheek stain for giving gorgeous colour and staying power.
7. Shu Uemura Skin Purifier Fresh Gentle Cleansing Oil, £28
This cleansing oil is her favourite way to get rid of all that stage make-up before bed.
8. Minx Professional for Naja, from £25, stockists: 0113 217 3813
Katy loves her Minx nails and often tweets about her custom-made designs.
Do you have a beauty favourite? Why not tell us about it in the comments box below...
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