Prime Day is exclusive to Amazon’s Prime members and is clearly designed to reinforce loyalty among existing members and recruit new ones ahead of next week’s event (15 July).
The company is cutting the price of Prime membership by £20 to £59 for anyone who joins from now until this Wednesday (8 July).
The online retailer, which is also celebrating its 20th birthday next week, said that shoppers will be able to find more than double the volume of deals offered on Black Friday, with Lightning Deals and six Deals of the Day.
Price-cuts will span categories including electronics, toys, video games, films, garden, sports and beauty.
Amazon has launched a video ad on YouTube that explains Prime Day and shows how it commissioned eight artists, from countries including the UK, to create "interpretations of #PrimeLiving".
The retailer is also kicking off a global competition with a prize of $10,000 (£6,428) in Gift Cards, inviting Prime members to send photos expressing how Prime has helped them, using the hashtag #PrimeLivingPhoto. One winner will be selected from each participating country.
Greg Greeley, Amazon Prime’s vice-president, said: "Prime Day is a one-day only event filled with more deals than Black Friday, exclusively for Prime members around the globe.
"Members tell us every day how much they love Prime and we will keep making it better.
"If you’re not already a Prime member, you’ll want to join so you don’t miss out on one of the biggest deals extravaganzas in the world."