An extra 4000 seats a week will be available after a phased increase which will see capacity rise by 25% by January.
The additional flights will begin from the end of this month when a Boeing 767 aircraft is introduced to Glasgow.
Business leaders who have lobbied for improved connections to the UK capital have welcomed the move, which comes after rival BMI axed its daily service to London from Glasgow in March, leaving BA as the only provider.
The expansion of BA's services has been helped by a decision to base a 252-seat Boeing 767 – with 113 more seats than the Airbus it replaces – at Glasgow.
It will fly four return journeys from October 31 between Glasgow and London, with the number of return flights between the cities increasing from 57 to 67 a week by January.
Glasgow Chamber of Commerce chief executive Stuart Patrick said: "I've been getting regular calls from business leaders emphasising the need to widen the offer for Heathrow services and so we are naturally delighted to see British Airways responding."
Passengers have struggled to get a flight unless they booked well in advance after BMI's quit the route.
Tony Davies, British Airways regional customer services manager for UK regions, said: "Because the changes in the Glasgow market came late as we approached the summer 2011 season, we reacted quickly and were able to increase capacity by more than 5% on the Heathrow service.
"Now, having had time to look at our schedule in detail, we have been able to add a further 4000 seats."
Glasgow Airport managing director Amanda McMillan said the decision was "tremendous news".
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