Customers were still unable to shop on the website this morning, but Iceland has now fixed the issues.
Iceland said on its Twitter page that the website experienced "a few hiccups" because so many people were trying to place their Christmas food orders.
The extra traffic crashed the website, it added.
Customers said they were being placed in a virtual queue mid-way through their online order and unable to finish their shopping.
This morning, shoppers couldn't access the website at all, with a message saying that the website was undergoing "essential maintenance".