While just 13 per cent of men are aware it could cut a mother's risk of developing breast cancer.
It is the most common form of cancer in women, with about 45,000 cases diagnosed in Britain each year.
It is a real concern that so many women are unaware of a simple way they could help protect themselves, said Lucie Galice, from the WCRF.
"The evidence on this is convincing and this is why we recommend that – if they are able to – mothers should aim to breastfeed exclusively for the first six months and then continue with complementary feeding after that," she said.
"This means that many new mothers are making choices about whether to breastfeed without knowing it can help reduce cancer risk for them and their child."
Of the 1,998 people surveyed, 19 per cent thought breastfeeding reduced a woman's risk of breast cancer, while 25 per cent thought it reduced a child's risk of being overweight.
The World Cancer Research Fund (WCRF) conducted a survey which showed that 75% of women do not know that breastfeed thing their baby helps cut their risk of breast cancer.
The numbers were even worse for men, as 87% had no idea that breastfeeding could help the mother cut the risk of developing breast cancer.
The survey also found that nearly 70% of women are unaware that breastfeeding helps their babies by lowering their risk of being overweight.
The survey was carried out following studies which has clearly shown the benefit of breastfeeding for mothers.
Breast cancer is diagnosed quite often and is one of the most common forms of cancer among women.
Education is needed to help teach mothers the benefit of breastfeeding not only for themselves, but for their babies too.