The two firms were one entity until 2015
Online auction site eBay has announced a new global payments processor.
It has signed an agreement with Adyen to become its primary payments processing partner.
However PayPal will still be a payments option at the checkout for eBay buyers.
When customers checkout, they will have the option to stay on eBay and use Adyen's services - or leave the website and use PayPal.
eBay says its operating agreement with PayPal remains in place through mid-2020.
PayPal says it will be available, as a way to pay on eBay, through July 2023.
eBay and Paypal were part of the same company for 13 years, but split into standalone businesses in 2015.
In a statement, eBay says: "In a rapidly changing and competitive ecommerce landscape, shoppers expect to be able to both shop and checkout on the site on which they transact.
"As eBay intermediates payments, shoppers will be able to complete their purchases within eBay.
"As a global marketplace that operates in over 190 markets, eBay also must continue to provide localised payment options for buyers and sellers that are tailored to their unique needs.
"Over the past three years, eBay has transformed its business to drive the best choice, most relevance and most powerful selling platform.
"Building out eBay’s payments capabilities is the next step in the company’s strategy, with the goal of driving significant benefits and efficiencies for its buyers and sellers globally."
"PayPal will remain an important partner to eBay", it adds.
eBay claims these changes will see lower costs and more control for sellers, while buyers will have more payment options at checkout.
On Wednesday, PayPal announced its fourth quarter revenue grew 26% to US$3.74bn (€3.00bn).
Dan Schulman, president and CEO of PayPal, said: "PayPal had a transformative year in 2017. We brought record numbers of new customer accounts to our platform by democratising financial services for consumers and commerce capabilities for merchants.
"We also substantially expanded our opportunities for future growth and redefined our competitive position through our successful partnership strategy driven by our open platform architecture".
PayPal has operations in Dublin and Dundalk, while eBay also has offices in the capital.