This month was the London airport's 32nd consecutive month of passenger growth, following its milestone in October of 14 million passengers.
LLA is currently investing more than £110m to increasing the airport's capacity from 12m to 18m passengers per year by 2020.
The upgrades include improvements to the airport's offerings, transport links and customer experiences.
Read more: Four arrested in Luton over terror offences
To improve customer experience, LLA will install five new ePassport gates this month, which give European Economic Area nationals the option to pass through automated border control using their biometrics. The airport now has a total of 15 ePassport gates.
The airport will also start providing complimentary plastic bags for customers travelling with hand-luggage liquids this month.
LLA is the only London airport without an express-style rail service from central London, and now it is calling on government to use the upcoming East Midlands rail refranchising process to address that.
Nick Barton, chief executive of LLA, said:
Introducing four fast trains per hour through the new East Midlands franchise would benefit passengers, the local community and fare box revenues at no cost to government.
A rail link planned by Luton Borough Council for £200m between Luton Airport Parkway station and the terminal will further improve LLA's connection to London with a journey time of less than 30 minutes from the centre of the city.