Passengers using Heathrow rose by 2.2% to a record of 33.6 million in the first half of the year.
Figures from owner BAA show that the number of passengers using Heathrow and Stansted increased by 0.8% to 41.8 million in the six months to June 30.
Half year pre-tax losses were reduced by almost £80 million to £50.9 million for the two airports.
BAA chief executive Colin Matthews said: “Higher passenger numbers and increased yields are driving revenue growth which is being invested in new facilities for passengers.
“Passengers tell us they are noticing the improvements with Heathrow receiving its highest ever passenger satisfaction scores in the two most recent quarterly Airport Service Quality surveys.”
He added: “We are pleased that Olympic arrivals have gone smoothly so far but there is lots more to do.
“London 2012 is Britain’s biggest peacetime transport challenge and we are spending more than £20 million to ensure Heathrow is ready for its busiest ever period, including building a temporary Games Terminal; preparing to host remote check-in at the Olympic Village; and training more than 1,000 volunteers who are giving a warm welcome to athletes on behalf of London.”