Cancer Research UK will allow donors to choose exactly where their money is spent with a new online system to be launched in March.
The scheme, called My Projects, is already on trial.
It allows supporters to specify that their money should be spent on researching specific types of cancer, or on funding cancer nurses.
The initiative also provides information about scientific research projects that are taking place and lets donors give directly to them.
Kevin Waudby, head of innovation at CRUK, said that in the past only major donors had been able to specify where their money was spent.
"Online fundraising means charities have to have closer relationships with all of their supporters and let them all have a say in what happens to their donations," he said.
Waudby said the aim of the new system was to bring in new donors rather than to encourage existing donors to give more.
A trial website for the scheme has been put in place, and the new site will be launched officially in March next year.