The new shop will create more than 500 new jobs, while 430 colleagues will transfer from the existing New Street store.
Around 300 shoppers, some who arrived as early as 6am, queued up to enter the outsize store, which opened up 12 minutes early at 9.48am on Thursday. Here's a closer look inside:
The five-floor building features three food venues, water fountains as well as charging points for your phones.
While it will include all your favourite Primark products it will also have the retailer's largest ever beauty studio for nails, make-up, hair, eyebrows and more.
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They've thought of everything, including a Disney cafe!
If you end up spending so much time inside the store you realise that your hair has grown unruly, then it has a barbers inside so you can get a trim.
As well as the Disney cafe, it also has a Disney shopping area and a Hogwarts Wizarding World section. If you can't find what you are looking for a custom lab will print personalised t-shirts and other garments.
The new shop will create more than 500 new jobs and 430 current Primark staff members will be transferred to the store to help staff it!
The store will also offer shoppers the opportunity to donate pre-loved clothes and shoes - of any brand - for recycling.
The store covers 160,000 square feet which makes it the biggest of the high street retailer's 365 stores across Europe and the United States.
Primark's director of new business development, Tim Kelly said: "They can spend time with friends and family, eat great food, recharge and have fun, and find everything under one roof.