Shares in the London and Amsterdam listed business rose by nearly a fifth on Wednesday.
Starting today, Amazon Prime subscribers in the States will also get a free Grubhub+ membership for a year.
It means they will not have to pay for the delivery fee that would normally be charged when ordering a takeaway.
Just Eat Takeaway bought Grubhub last year in a 7.3 billion dollar (£5.75 billion) deal. But it has faced criticism from investors over the deal.
One activist investor, Cat Rock Capital, has built a more than 5% stake in the company. But it is highly critical of management, and in April called on shareholders to fire the board.
Cat Rock also heavily criticised Just Eat Takeaway’s (Jet) disclosures in the run-up to the Grubhub deal.
“Jet’s management and supervisory boards torpedoed the company’s share price by providing a misleading outlook on the company’s profitability in advance of the Grubhub shareholder votes in October 2020 and June 2021,” the investor said in April.
“These misleading financial disclosures led to two massive profit downgrades in 2021 and the complete loss of trust in the company’s financial guidance.”
It has been a bruising year for the company’s shares. They have dropped nearly 80% of tier value since last July, despite a big rally after the Amazon deal was announced on Wednesday.
The deal led to an increase in the share price of nearly one fifth.
Just Eat said that the Amazon deal will renew automatically each year until one of the companies cancels it.
Amazon will take a 2% stake in Grubhub, and have the option to buy another 13% of the shares, based on how many customers take up the new offer.
Just Eat thinks that it will expand Grubhub+ membership and have a neutral impact on Grubhub’s earnings and cash flow this year.
It will bring in increased cash flow from 2023 onwards.
Grubhub chief executive Adam DeWitt said: “I am incredibly excited to announce this collaboration with Amazon that will help Grubhub continue to deliver on our long-standing mission to connect more diners with local restaurants.
“Amazon has redefined convenience with Prime and we’re confident this offering will expose many new diners to the value of Grubhub+ while driving more business to our restaurant partners and drivers.”