The US ecommerce giant will be the launch sponsor for the new Capital London Breakfast Show with Roman Kemp, which debuts on Tuesday (2 May).
EBay has already proved to be a major investor in commercial radio, upping its annual spend by 500% to £6m last year, according to Nielsen figures from the Radio Centre.
Mike Gordon, the chief commercial officer at Global, the owner of Capital, said: "EBay is seeking to reach savvy 15- to 34-year-old listeners, making this partnership a great fit with Capital’s audience."
As part of the deal, eBay will have a presence on Capital’s breakfast show web pages and on social channels and mobile apps.
Gareth Jones, marketing director, eBay, said: "Partnering with Global’s Capital network presents us with an opportunity to re-educate audiences about who eBay is in 2017."
EBay claims to be "a shopping destination like no other...The sheer range of items available to buy means that shoppers can find exactly what they are looking for."
Online retail was the fastest-growing category in the commercial radio industry in 2016, upping ad spend 90% from £6.5m to £12.4m.
That helped commercial radio revenues hit a record £645.8m last year.
According to Rajar, live radio continues to reach 89% of the population and is second only to TV.