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They can do so by replying to tweets containing a link to an Amazon product with #amazoncart in the US and #amazonbasket in the UK.
Users will still need to go to Amazon to pay and complete the purchase.
The move comes as firms are looking at ways to use social media platforms as tools to attract customers.
"Ultimately it is all about conversations that people are having on various platforms such as Twitter and Facebook about what interests them," said Sanjana Chappalli, Asia-Pac head of LEWIS Pulse, a firm specialising in digital marketing.
"Brands are keen to tap into these platforms, not least because they have hundreds of millions of active users."
The move also comes just days after Twitter reported a net loss of $132m (Â£78m) for the first quarter.
The number of active users on the social network reached 255 million in the first three months of 2014, up 5.8% on the previous quarter. However, that growth was below analysts' expectations.
There have been concerns that the pace of growth the Twitter has seen in the past years may be slowing, which may hurt its revenues.
Ms Chappalli said the tie-up with Amazon was likely to help Twitter engage its users better and as result attract more advertisers.
"For Twitter the revenue model is based on not just on the number of active users but also on how much time those users spend on the platform," she said.
"This deal provides them a good chance to leverage on other sites such as Amazon to help push the engagement rates up."
Meanwhile, Amazon said the partnership would make it easier for users to purchase products they saw on their Twitter timeline.
"No more switching apps, typing passwords, or trying to remember items you saw on Twitter," the firm said in a video it posted about the tie-up.

Online retailer Amazon has announced a partnership with Twitter that allows users to add products to their shopping carts by tweeting a special hashtag.