The islands of Burhou and a stretch of Alderney's coast will be officially recognised for their environmental importance on Thursday. The area is being given Ramsar status because it is home to seabird colonies of global significance.
The United Nations' Ramsar Convention aims to promote the conservation of wetland habitats around the world.
A team of volunteer experts has been working for months to record the wildlife found at the site in Alderney.
Work has now begun on a guide and maps to give visitors more information about the area.
It is hoped this achievement will also help to attract eco-tourists to the island and help boost its economy.
Other Ramsar sites in the British Isles include the Severn Estuary, Lindisfarne and Loch Lomond.