The Luton Airport Express by East Midlands Railway (EMR) will take passengers from St Pancras station to the airport in 30 minutes.
After arrival, passengers will be taken to the LLA terminal in less than four minutes by the Luton Dart, a new automated, electrically powered people mover which replaces the previous bus transfer service.
The addition comes after the airport welcomed 1.2 million passengers in March, a 49% increase on the same month last year.
According to the latest passenger data, the March total brings the number of passengers who have used LLA in 2023 to almost 3.3 million and marks the second consecutive month the airport has exceeded one million passengers.
The airport saw more than 420,00 passengers during February half-term week, with demand for ski travel leading to an increase in popularity for flights to Austria, France and Switzerland.
Neil Thompson, operations director at LLA, said: "It’s great to see a continued rise in our year-on-year passenger numbers, a demonstration of the obvious appetite for air travel in 2023, and London Luton airport’s appeal.
"At LLA we’re focused on providing the simplest and friendliest end-to-end passenger experience, and this includes enhancing connectivity to the airport."
