According to the Evening Standard, the cash will be distributed in the form of grants to community groups bidding to run the event.
The Mayor has also offered Trafalgar Square for use during the event free of charge.
He has stepped in to help the event after it ran into financial difficulties.
Andrea Minichiello Williams, chief executive of Christian Concern is unhappy that taxpayers' money has been spent on the Pride events.
"The Mayor of London is throwing public money at an event which does not have the backing of a large section of the public," she said. "I hope those Londoners who disagree with Mr Johnson will let him know."
Mr Johnson has defended support for the event, saying it was a "key event" in London's cultural calendar.