The company, whose customer satisfaction levels were also at an all-time high, posted an 8% rise in revenues to £2.46 billion, while it returned to the black at an underlying level with profits of £46.4 million.
Heathrow has reported higher revenues and profits after a record 70 million passengers used Britain's biggest airport during 2012.
However the airport is operating at close to capacity and the company warned this would limit the UK's ability to trade with emerging economies. There were 471,341 flights during 2012, just below Heathrow's cap of 480,000 a year.
The results from the former BAA company include Stansted Airport, which was sold after the year-end to Manchester Airports Group for £1.5 billion. Stansted's passenger numbers declined 3.2% to 17.5 million last year.
The company predicted more strong growth in Heathrow's turnover this year and said construction of the new Terminal 2 should be completed towards the end of 2013, with operations commencing in mid-2014.
The project accounted for a large slice of the £1.1 billion invested in the airport during 2012, an increase of more than 30% on a year earlier.
Heathrow achieved an all-time record passenger satisfaction score in a survey produced by the Airports Council International for the third quarter, but the percentage of people passing through central security within the prescribed time was below last year's level at 92.8% in 2012.
Meanwhile, Heathrow's retail income increased 4.4% to £6.21 per passenger, while the figure was 2.8% higher at £4.27 for Stansted. At the start of last year, a third runway at Heathrow was not under consideration but the establishment of an independent commission tasked with looking at options for maintaining the UK's status as an international aviation hub has encouraged the company.
The group said: "Unlike its rivals in France, Germany, the Netherlands and Dubai, Heathrow is full and its capacity constraints prevent any meaningful increase in the numbers of flights and routes. This means the country's ability to trade with emerging economies is constrained, with potential long term consequences for UK trade, jobs and economic growth."
The figures show the company incurred a net £25 million of Olympic-related costs, such as Heathrow's temporary Olympic terminal, professional consultants, staff bonuses and overtime costs. When including interest payments on debt and one-off items, Heathrow reported pre-tax losses of £32.8 million, compared with a deficit of £255.8 million a year earlier.