The British-born presenter loves Pantene Pro-V One Minute Wonder Ampoules, £4.49 for 3.
As an ambassador for the company, it was pretty inevitable that her top pick would be straight from the high street haircare range but at under a fiver, this is one celeb buy we're dying to try!
"They are a wonder treatment! You just apply one to damp, clean hair, leave for a minute and then rinse to give a hair health boost in one go. They are brilliant for travelling too - if I'm going away for a long weekend I can put a couple of these in my hand luggage," says Cat.
The jet-setter also uncovered the contents of her holiday beauty kit:
Rodial Glam Balm Multi, £49
"This is the richest and most nourishing moisturiser I've ever tried. It's perfect for keeping my skin super-hydrated when I'm on the plane."
Caudalie Beauty Elixir, £11
"There's nothing like a refreshing spritz to clear the head and the essential oils in this spray take care of my skin too."
L'Occitane Almond Supple Skin Oil, £32
"I'm a big fan of oils for my face, body and hair. This one smells exquisite and I make sure I apply it fresh out of the shower for added hydration."
Clinique Take The Day Off Cleansing Balm, £20.50
"This is the quickest, most effective way of removing make up I've ever found! Apply the balm, massage it all over your face then simply take a hot wash cloth and remove. Every last trace of make-up is gone in one easy step!"
Bobbi Brown Foundation Stick, £28
"These are so easy to use, even if you're not a professional. They're easy to blend, give great coverage and they're really convenient. I carry two - one light and one slightly darker - so I can customise my own shade."
Stila Lip Glaze, £15
"The colours in this range are superb. There's everything from delicate nudes to eye-popping candy hues."
Clarins Sun Protection, from £16
"Just the smell of this transports me to sun-drenched beaches and sandy shores! I'm outside a lot in Los Angeles so I constantly wear sun protection on my face and chest."
What is your top holiday beauty buy? Tell us below as the best comment from across the site each week wins £50!