The Amazon Fresh service, that previously cost an extra 14.99 a month, allows users to order from thousands of products including a wide range of fresh produce.
Delivery times vary based on the customer's location, with one and two-hour deliveries available in more than 2,000 cities and towns across the US, although there are suggested plans to roll out the one hour scheme more widely in the UK.
Food orders will have to be at least $35, or $50 in New York, before they qualify for free delivery.
Amazon Prime members can benefit from free grocery deliveries within an hour, as the online retail firm makes Amazon Fresh a standard benefit of the subscription.
'Prime members love the convenience of free grocery delivery on Amazon, which is why we’ve made Amazon Fresh a free benefit of Prime,' said Stephenie Landry, Amazon's VP of Grocery Delivery.
'Grocery delivery is one of the fastest growing businesses at Amazon, and we think this will be one of the most-loved Prime benefits.'
Amazon Fresh will be joined in Prime by the Whole Food Markets service, allowing customers to shop their local Whole Foods store via the Amazon website or app.