Bright pink bins are being installed at some recycling sites in a west London borough so women can drop off unwanted bras.
Some of the underwear will be cleaned and repaired and then sent to women in Africa to re-use.
For every 17 bras that are recycled in the borough of Hilllingdon, £1 will go to the Breast Cancer Campaign charity on behalf of the council.
The banks can be found at 10 locations until the end of October.
Tina Toland, a Hillingdon borough resident who has fought breast cancer, said: "This is a great idea and it's all about raising awareness, which is so important.
"The message needs to reach people. Hopefully this bra recycling scheme is one way to help achieve this."
Councillor Sandra Jenkins said: "We will be trialling this for the rest of October for Breast Cancer Awareness Month and will be look at making the bra banks a more permanent fixture if they are a success."