Heathrow Airport made a pre-tax profit of £186 million in the first half of the year compared with a £51 million loss in the first six months of last year.
Passenger numbers were up 2.4% to 34.4 million and revenue rose 9.2% to £1.149 billion.
Chief executive Colin Matthews said: "Performance at Heathrow this year is encouraging.
"The number of passengers using the airport increased, passenger satisfaction hit record levels and we maintained solid delivery of our service standards.
"Our earnings support the investment made in Heathrow and that continues with the new Terminal 2: The Queen’s Terminal opening in June next year. We want to build on our achievements and continue that progress over the next five years, which is why we’ve submitted fresh plans to the CAA for a further £3 billion of investment, if returns to investors are fair and competitive."
Manchester Airport is also enjoying rising passenger numbers it was announced today, with 2.1 million passengers using the airport during June, a 4.1% increase over the same month last year.
The airport said it was the 13th consecutive month of year on year growth for Manchester. Figures released by the CAA show the average UK airport growth last month was 3.2%.
