A total of 1,073,541 travellers passed through the airport, generating an 8.7 per cent growth on the same period last year.
September was the fifth month in a row that the airport had over one million passengers, a feat never achieved before and unrivalled by any other airport in Scotland.
Gordon Dewar, Chief Executive of Edinburgh Airport said: “It’s fantastic to see our new routes are working well for our passengers.”
The success was linked to a 10.7 per cent growth in domestic passengers due to more people travelling to London City with BA Cityflyer and Flybe and to Stansted with Ryanair.
International flights also saw a growth of 7.2 per cent due to higher traffic on Ryanair flights to Dublin, and across their wider route network.
Norwegian, Scandinavian Airlines’ Stockholm route and Etihad’s service to Abu Dhabi were among the busiest.
Dewar added: “We’ve listened to our passengers for domestic connectivity and start an Edinburgh to Liverpool service with Flybe at the end of the month.
“We’re also launching Stuttgart with EasyJet in early November. It’s great that we can continue to announce new routes and services throughout the winter months.”
In 2014, 10.2 million passengers used the airport.
The airport is on track to enjoy its busiest year in 2015, with a moving annual total of 10.89 million passengers.