British Airways, Iberia, Aer Lingus and Vueling will debut inflight Internet on intra-European flights from mid-2017, using a mix of Inmarsat satellite and 4G broadband connectivity.
Speeds available to travellers are expected to support streaming video and other high-bandwidth activities like sending and receiving large email attachments from multiple devices.
The installation will span 341 single-aisle aircraft, including 132 from British Airways, 45 of Iberia and 39 from Aer Lingus, plus 125 of low-cost airline Vueling's jets.
This is a "game changer for the millions of airline passengers that have been cut-off from fast, reliable and consistent broadband access during flights in Europe," said Leo Mondale, President of Inmarsat Aviation.
British Airways will be the first of IAG's four airlines to get connected within Europe with plans to launch the service on an Airbus A321: such as often found flying between London Heathrow and Rome.
It's not yet known if inflight Internet will be extended to twin-aisle aircraft such as BA's Boeing 767s which also ply similar routes, so for a greater chance of your flight having WiFi next year, stick to the smaller planes.
Pricing details are yet to be revealed, although it's expected that airlines may charge more to users taking advantage of high-speed streaming than those merely browsing the Web.
British Airways also plans to offer inflight Internet access aboard its long-haul flights from early 2017, including on its Sydney-Singapore-London route.