Operators agreed to donate all profit from the flagship Britannia Stakes to charity, but when favourite Hayley Turner on Docklands won, this led to a loss for bookmakers.
However, the group honoured a pledge to make a bumper donation instead.
Flutter, Bet365, Entain, 888 William Hill, Kindred, Betway, Rank Group, LivescoreBet, Virgin Bet, Tote, Fitzdares and Bet with Ascot all took part.
Funds were split between SportsAid, the Holocaust Educational Trust, Cystic Fibrosis Trust, SAS Regimental Association, Ascot Racecourse Supports and Together for Looked After Children.
Over £5.9m has been raised for charity through the Britannia Stakes and virtual Grand National since the BGC formed in 2019.
Last year’s Britannia Stakes initiative raised £1.2m after victory by 14-1 shot Thesis led to a big profit for bookmakers.
Huge donation
“It’s great news that BGC members have once again made such a huge donation to a range of good causes,” BGC chief executive Michael Dugher said.
“I am sure that the money we raised will once again make a massive difference to the incredible work done by all the charities involved.
“I am delighted that BGC members have now raised close to £6.0m for charities up and down the country.”
Ascot Racecourse chief executive Alastair Warwick added: “We are hugely grateful for the support of the BGC and its members again this year with the Britannia Stakes initiative.
“Although not a profitable winner, with Hayley Turner winning the race it was still a hugely positive story for racing and the donation agreed by bookmakers will go a long way to supporting these charitable causes, including our own Ascot Racecourse Supports programme.”