Head gardener John Anderson said: "We are thrilled to have been recognised by the International Camellia Society for our Camellia Collection."
He added: "Lionel de Rothschild planted hundreds of camellias when he acquired the Garden after the First World War, and his family and subsequent head gardeners have maintained this planting tradition ever since.
"Exbury now has three atmospheric Camellia Walks, offering our visitors and camellia enthusiasts an unrivalled opportunity to discover the flower's many distinct forms in a beautiful woodland setting.
"We are incredibly proud of this award, especially as there are only 30-odd gardens in the world with this honour."
In early March Exbury opened the new ‘Gilbury Lane’ garden, a showcase for the Trehane Collection of Camellias, featuring hundreds of named and labelled varieties.
Anderson said there has been a Camellia renaissance recently.