The last people on the plane will be those who bought the cheapest, hand-baggage-only fares.
"Group boarding simplifies the process, making it easier for customers to understand the boarding sequence at the gate," British Airways said in an internal newsletter, quoted by the Times of London.
The airline confirmed passengers requiring special assistance, and those travelling with young children, will still be given priority boarding.
But the new system has split opinions.
Supporters said it would bring the British flag carrier in line with other major airlines, including American Airlines, Iberia and Qatar Airways, as well as budget airlines EasyJet and Ryanair, which use group boarding to speed up the boarding process.
And airlines, including British Airways, typically prioritise first and business class travellers and members of airline loyalty schemes.
Some celebrated the news on Twitter.
"I shall enter triumphantly at the very end wearing a shirt that says 'Yay! I paid less than all you suckers'," one person said.
Another said: "If some idiot pays more to sit in a stationary plane waiting for those he considers socially inferior, so what?"
Others decried what's been dubbed the "poor doors" and accused the airline of "shaming the poor".
"What happens if you got it free with frequent flyer points? Will you have to do the walk of shame?" someone tweeted.
Another said: "This idea of boarding people by their ability to pay is unfair. It should be done by rows if you wish to board more quickly. #britishairways #snobbery #shamingthepoor".
Said another: "Of course, the logical way to load a plane would be back to front but that would mean first class got on last And We Can't Have That Can We".
Someone else said: "If you've paid for Hand Baggage Only by the time you board (last) they'll be no space left in the overhead lockers," they tweeted.
A spokesman for British Airways told the Times: "We are always looking at ways to improve the airport experience for our customers.
"Next month we are looking at introducing new boarding procedures to further improve the customer journey by creating a number of groups to speed up the process.
"This method has been used by airlines around the world for a number of years, including by our partners American Airlines, Iberia and Qatar."
