A survey of more than 2,000 people found two thirds could not link any celebrity with a list of seven well-known charities and aid organisations that they worked for.
Stars did not support charities for self promotion, but this was the unintended outcome of their work, researchers concluded.
But charities told The Yorkshire Post that there was plenty of evidence to show that their high-profile ambassadors do make a huge difference to their campaigns.
The seven organisations mentioned in the survey were Action Aid, Amnesty International, CAFOD, Christian Aid, Oxfam, Save the Children and the Red Cross.
Speaking about their study, Professor Dan Brockington of the University of Manchester, and Professor Spencer Henson of Sussex University, said: “Our survey found that while awareness of major NGOs’ (non-governmental organisations) brands was high, awareness of celebrity advocates for those brands was low.
“Instead it was plain from the focus groups that most people supported the charities that they supported because of personal connections in their lives and families which made these causes important, not because of the celebrities.
“The evidence suggests therefore that the ability of celebrity advocacy to reach people is limited and dominated in Britain by some extremely prominent telethons and the work of a few stars.
“Regardless of what celebrities may want in terms of publicity - and the interviews suggest that many would seek to maximise the attention given to their cause and not to them - it is clear that the celebrity can often do better out of this attention than their causes.”
Human rights organisation Amnesty International has called on the support of the likes of John Cleese, Patrick Stewart, Elton John, Madonna, Bob Dylan and Kiera Knightly over the years.
Allan Hogarth, the NGO’s head of policy, insisted that celebrity support is “hugely valuable”.
“When a celebrity lends their voice to one of our campaigns the impact can be tremendous,” he said. “For instance, after John Cleese and Rowan Atkinson helped with the Secret Policeman’s Ball shows (in the 1970s), public support for Amnesty increased by 700 per cent and the profile of human rights went through the roof.”
Aid and development charity Oxfam has drawn on its own group of well-known figures for public support, including Stephen Fry who helped launch its biggest ever call for book donations in 2012. Oxfam said its high profile supporters enable the charity to bring issues like poverty and inequality to large, new and diverse audiences.
“Many of our ambassadors have supported Oxfam for years, and their commitment has made a huge difference to the lives of many thousands of people, by generating public awareness, campaigning and financial support,” Oxfam added.
Michelle Lowery, PR manager for ActionAidUK, said working with some of the UK’s best known faces had given the charity more credibility. She highlighted a recent celebrity visit to the Far East as proof of the difference it can make: “In 2012 we took the actress Samantha Womack to visit to our work in Myanmar, this was an integral part of a fundraising drive that signed up over 2,000 new child sponsors for children desperately in need.”
Save the Children, whose supporters include newsreader Sir Trevor McDonald, insisted that the passion and conviction of its celebrity supporters helped it gain national media coverage that it would not otherwise get.