Belfast rarely gets the transatlantic spotlight it deserves, which is precisely why frequent flyers who've cracked the code on this route tend to guard it jealously. There's no nonstop service between O'Hare and George Best Belfast City or Belfast International, so business class from Chicago to Belfast requires a connection — and after dozens of trips, I can tell you the smartest routing is through London Heathrow on British Airways, pairing a widebody transatlantic leg in Club Suite with a short domestic hop to Belfast. American Airlines and United both fly ORD-LHR nonstop with lie-flat business cabins, making a same-alliance or interline connection onto BA's Belfast shuttle a logical alternative if schedules align better.
The transatlantic segment is where the real decision-making happens. British Airways' Club Suite, with its sliding door and direct aisle access on the 787 and A350 fleets, remains the gold standard on this corridor and is worth positioning for even if it means a slightly longer layover at Heathrow. United's Polaris seats, found on its 787-9 and 777-300ER aircraft, offer similarly private suites with excellent bedding, while American's Flagship Suite on select 777s and 787-9s is a strong option if your itinerary routes through Philadelphia or another East Coast gateway instead. My insider tip: build in at least a 2.5-hour connection at Heathrow if transferring to the Belfast leg, since T5-to-T3 or T5-to-T5 transfers for BA's CityFlyer-operated Belfast route can eat time during peak security hours, particularly in summer.
Seasonality matters more on this route than travelers expect — January, February, March, October, and November consistently offer softer premium cabin demand, since Belfast's tourism peaks are spring and summer while Chicago-London business traffic dips outside major conference seasons. Given how thinly these premium cabins sell on connecting itineraries, setting up fare alerts for ORD-BFS business class is genuinely the smartest way to catch the pricing windows before they close.
