The Spanish clothing retailer revealed a newly refurbished store, which was formerly Banana Republic.
Moving from its former premises next door, Zara now has 3,877 square metres devoted to the latest trends and outfits.
The move from its old 2,879 square metre store means that the west London branch is now the UK's biggest Zara.
Dozens of Zara fans took to Get West London's Facebook Page to share their delight of the store opening.
Sian Clements wrote: "Yay! I might never leave."
Meanwhile, Elaine O'Reilly said: "You would be in heaven there."
Noor Al-Safi added: "Yes! We walked past it last week, it's huge.
"Zara shop soon, I want to check it out."
Zara fans also shared their reaction on Twitter.
One wrote: "The biggest Zara store in [the] UK is now in Westfield White City. Dream come true that it's near me."
Camilla Gee said: "Way too excited that they have expanded the Zara in Westfield."
Zara fans will be delighted to hear the new store is also home to exclusive clothes and accessories that will not be available elsewhere.
On top of the womenswear, menswear and kidswear, an additional crafted accessory section is offering shoppers exclusive products.
While the new Westfield store is huge, it's still only half the size of the largest Zara in the world.
The branch based in Madrid, which opened earlier this month, is a whopping 6,038 square meters.
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