As part of its switch to using electric vans on rounds, it said it no longer needed the bikes and therefore wanted to donate them to a good cause.
The donation marks the 2,000th bike contributed to the foundation as part of the Bikes to Africa scheme.
Dawn Gallienne, Guernsey Post head of corporate management, wanted the bikes to go to a good home.
'We are really pleased to be donating the bikes to such a good cause,' she said.
'This is a goodbye to the bikes – this is a bit of an end of an era.'
The vans were needed due to an increase in parcel deliveries in the island, she said, but bikes are still used on four rounds in Town.
