The figure represents a healthy 16.9% rise on 2014.
Indeed the gateway recorded double-digit growth every month last year, including 18.9% in December, making it the fastest growing of the four major London airports in percentage terms in 2015.
According to London Luton Airport (LLA), "this significant growth comprised of increased capacity and new routes with established airlines and the arrival of no less than four new airlines".
The airport actually saw the launch of 20 new routes in 2015.
To meet rising passenger demand, LLA is currently undergoing a £110m redevelopment which, when complete in 2020, will equip it to handle up to 18mmpa – 50% more than today.
The transformation will including:
• A complete redesign of the terminal to create a quick, efficient, friendly and convenient passenger experience
• Doubling of the existing retail space, introducing exciting shopping and dining options, including a new executive lounge
• A new multi-storey car park with 1,700 spaces
• The addition of Oyster card services through to the terminal building
Transport access has already been improved through a major upgrade to junction 10a of the M1 and the introduction of overnight trains between St Pancras International and Luton Airport Parkway.
Nick Barton, CEO of LLA, said: “With more than 12 million passengers passing through the airport 2015 was a record year for LLA. But, while 2015 was the busiest year in our history, 2016 is set to be the most exciting as our £110m investment transforms the experience for our passengers.
“The redevelopment will also increase our capacity to 18 million passengers per year by 2020. The recent announcement that airlines Vueling and Transavia will both begin flights from LLA this year shows that demand is continuing to grow.”