More than 60 per cent of MPs said they found charity campaigns far more persuasive than the arguments put forward by corporate lobbyists.
Nine out of 10 said charities were good at engaging parliamentarians, compared with only 57 per cent who thought that businesses communicated with them effectively.
The poll also showed that charities are in more frequent contact with MPs. Fifty-one per cent of MPs said that they received 20 or more approaches a week from the sector, compared with 39 per cent who received the same level of contact from businesses.
A spokesman for the Sheila McKechnie Foundation, the charity that promotes effective campaigning, said: "On big issues such as climate change, African development and equality, campaigners have been setting the agenda for politicians."
But public affairs experts warned charity campaigners not to get complacent.
Sacha Deshmukh, managing director of public affairs consultancy AS Biss, said: "MPs know how to answer surveys to make themselves look good. Of course an MP is going to say that they listen more to a charity than to a corporate giant."
Deshmukh advised charities to make sure they have watertight campaigns if they want to catch the attention of MPs.
"Only then will you be able to achieve the real policy change that will help your clients and beneficiaries," he said.