Yes, you can absolutely use American Airlines AAdvantage miles to book flights on British Airways in 2026. As both airlines are founding members of the oneworld® alliance, their loyalty programs are highly integrated. You can search for and book British Airways "award seats" directly on the American Airlines website or mobile app. One significant detail to watch for in 2026 is that while the mileage cost might be reasonable, British Airways often passes on substantial carrier-imposed surcharges (often several hundred dollars) on transatlantic flights, especially in premium cabins like Business or First Class. To minimize these fees, many savvy travelers look for British Airways flights connecting through London to other European destinations or use their miles for short-haul "Reward Flight Saver" hops within Europe, where the taxes and fees are capped at a much lower flat rate. Additionally, your AAdvantage status (Gold, Platinum, etc.) grants you equivalent benefits on BA, such as priority boarding and lounge access.