Rebranded as Club Suites, the new business class seats all offer direct-aisle access, a suite door for greater privacy and flat-bed seats in a 1-2-1 configuration.
The new seats feature 40 per cent more storage, including a vanity unit and mirror, as well as WiFi, 18.5-inch inflight entertainment screens, and PC and USB power sockets.
The new A350 aircraft itself will benefit from reduced noise levels, high ceilings and ambient lighting. The plane has also been designed to have higher levels of humidity and refreshed air, with cabin pressure equivalent to an altitude of just 6,000 feet.
The airline, which is marking its centenary this year, will roll out the new suites in several phases, with the first A350 aircraft flying between London and Madrid in July.
From 1 October 2019, the new aircrafts will begin long-haul flights, while another two Boeing 777 aircraft will also be retrofitted with the new cabin.
The airline said it will begin fitting Club Suites on long-haul aircraft across the network from early 2020.
As well as a new 56-seat Club World cabin, the three-cabin A350 will feature the latest World Traveller Plus cabin with new furnishings, new amenity kits, an enhanced service and an improved dining experience. Customers will also benefit from high-speed WiFi.
BA has also announced this week that it be launching new direct flights to Dammam, its third route to Saudi Arabia.