Cliff Codona has become renowned for his campaign to allow gypsy families to stay at the Woodside caravan site near Hatch.
He lost the latest round in the court battle against Mid-Bedfordshire District Council earlier this month.
Mr Codona said: "I don't know if the UN really knows what it's taken on in asking me to be involved in gypsy issues."
He added: "The UK is pretty sick to death of looking at me, without the rest of the world wanting to know what I've got to say about things."
Mr Codona is already the chairman of the National Travellers Action Group in the UK, but will now act on behalf of Roma communities worldwide.
His MP, Alistair Burt, said: "In my dealings with Cliff Codona I've become aware that the authorities find him a very straight and honest representative.
"I can understand these qualities are appreciated by the UN."
Despite his new international role, Mr Codona still faces pressing problems at home.
He is among the 28 travelling families who bought the Woodside caravan site in 1997 and set up what they called a "pioneering community" there.
However, the council has said they do not have planning permission to live on the site all year round.
Bailiffs were sent there last November - but had to abandon attempts to break up the site as another High Court action was pending.