Etihad Airways will begin flying economy-only aircraft on some shorter routes from its base at Abu Dhabi in October.
The airline has previously built its reputation on a minimum two-class, full-frills service as has neighbouring Emirates, based in Dubai.
Etihad will operate the all-economy cabin on flights between Abu Dhabi and Alexandria (Egypt), Calicut and Thiruvananthapuram (Kerala, India), Colombo (Sri Lanka), Damascus and nearby Doha.
The carrier offers an extensive network of destinations from the UK via Abu Dhabi, flying from Heathrow and Manchester.
Etihad will initially configure two Airbus A320s as all economy with 162 seats, removing 20 business class places to add 42 in economy, but it plans to expand the economy fleet to 10 aircraft.