Flybe said it will have twice-daily flights from the north-east of Scotland from October 27, which adds to existing links between London City and Edinburgh and Inverness.
Saad Hammad, Flybe's chief executive, said: "Our announcement is a clear indication of our appetite to maintain momentum with our plans for growth and we look forward to welcoming many new passengers on board in October. The decision to add this flight to our already extensive point-to-point regional network reaffirms our commitment to listening to the needs of customers."
David Watt, executive director of IoD Scotland, said: "This is a vital link between the two most vibrant economic centres in the UK. Flights into central London direct from Aberdeen International Airport are particularly important to the oil and gas industry.
"Efficient connections between operational headquarters in the Aberdeen area and corporate and financial centres in central London are absolutely essential to the industry."
Separately, FlyBe said planes across its networks were now three-quarters full on average after it ditched loss-making routes and stepped up fare promotions.
The Exeter-based carrier's load factor jumped to 75.8 per cent in the quarter to June 30, up from 66.5 per cent a year earlier as it benefits from a turnaround drive that recently saw it post annual profits for the first time in four years.
Mr Hammad said first-quarter trading figures signalled further progress, helped by last summer's launch of 11 new routes and a major brand refresh in April when it unveiled aircraft in a new purple livery.
The airline, which serves about 35 UK airports having reduced its number of bases from 13 to seven in the last year, said passenger revenues per seat rose 9.5 per cent in the quarter to £52.79.
This was achieved after a recent route overhaul reduced capacity by 17.2 per cent to 2.5 million seats for the quarter to June 30.