The company has announced that it will charge charities a sign-up fee of £150 but will not levy any further fees, with immediate effect.
The move will be funded through a new ‘applications' system in which corporate brands will create adverts and the charities that raise funds through the site will be able to choose which of the adverts they want to place on their page.
Bmycharity previously charged an average of 65p on a £10 donation before Gift Aid was added. But Ben Brabyn, managing director of the firm, said the time was right for a "grand opening-up" of fundraising sites.
"Our aim is to make sure online fundraising grows its share of the market over the next few years," he said.
"When donors know there isn't somebody else taking a cut of the money they are giving, they are likely to be much more comfortable with using a service. So I would be very happy if Justgiving and Virgin Money Giving started operating like this too."
Both Justgiving and Virgin Money Giving told Third Sector they did not intend to change their charging structures.
A spokesman for Justgiving said: "At this point in time, we believe the transaction fee model remains the best and most sustainable model.
"We have considered advertising in the past, but our users and charities have told us that it impacted too much on the user experience."
A Virgin Money Giving spokesman said: "We welcome Bmycharity's innovation, and we think choice is good for the sector.
"But we are comfortable with our pricing structure because it is transparent."