Cancer Research UK has joined charities such as the National Trust, the NSPCC and Scope in supporting the self-regulatory scheme. A CRUK spokeswoman confirmed: "We will be joining imminently."
Jon Scourse, chief executive of the FSB, said the delayed scheme had "turned a corner" now that so many big charities were on board.
Adverts will run in The Guardian, The Independent, The Daily Telegraph, The Times, the Daily Mail and three Sunday broadsheets.
Giles Pegram, director of fundraising at the NSPCC, will join Scourse as spokesman for the campaign in media interviews.
Since the scheme opened for membership in April last year, 215 charities have joined. Numbers were boosted after the FSB revised its membership contract to omit a requirement for members to ensure volunteer fundraisers complied with codes of practice.