The busiest day of the month was 1 August, with more than 270,000 passengers passing through its terminals.
Also, T5, recorded a new single-day record on 22 August with over 112,000 travellers passing through.
The airport says growth was mostly driven by long haul traffic to Latin America and Asia as well as the Middle East.
“This is an outstanding achievement, made possible by the collective efforts of our colleagues, airline partners and the wider airport community,’ said airport CEO, Thomas Woldbye.
For security screening, Heathrow said 96% passed through within five minutes.