Heathrow airport more than doubled operating profit from continuing operations in 2013's first half, to £373 million ($573 million).
Turnover increased 9.2% to £1.1 billion.
The airport operator's pre-tax profit of £186 million - which reversed a loss of £51 million in the six months to 30 June 2012 - was aided by the sale of Stansted, from which it netted £279 million.
Passenger numbers grew 2.4% to 34.4 million, and load factor rose 1.2 percentage points to 74.4%.
Heathrow says growth was driven by European passengers, up 4.9% to 14.3 million, and by British Airways' acquisition of BMI routes last year.