A vote in the 192-nation General Assembly saw 180 countries come out in favour of granting the EU 'super observer' status, which does not give the bloc voting rights but will allow the High Representative to speak on behalf of the European Union.
No country voted against and only Zimbabwe and Syria abstained. The remaining 10 were not present at the vote.
Despite boasting new institutions introduced by the Lisbon Treaty (see 'Background'), the EU has thus far only been able to speak in the UN General Assembly through the ambassador of the country holding the bloc's rotating presidency.
An attempt last year to give Ashton speaking rights in the UN failed due to opposition from developing countries who feared the EU would be granted privileges that their regional organisations do not have.
Reportedly, the breakthrough came following heavy lobbying by the EU, the price of which means that other regional groups such as the Arab League, the African Union or the Caribbean Community are now likely to seek and will probably obtain similar status.
Addressing the General Assembly after the vote, Ashton said the resolution will enable EU representatives to promote the bloc's positions with a "clearer voice".
"I believe in the collaboration between the European Union and the United Nations," she said, "and I have made it part of my remit to ensure that the European Union works as closely as possible with the United Nations as we seek to rise to the challenges that we face across the world," Ashton said, quoted by AP.
European Council President Herman Van Rompuy welcomed the vote, which according to him had conferred recognition on the EU as a global actor at the United Nations.
With this resolution, the General Assembly acknowledges that since the entry into force of the Lisbon Treaty, the president of the European Council, Herman Van Rompuy, the High Representative of the Union for Foreign Affairs and Security Policy, Catherine Ashton, the European Commission and the EU Delegations have represented the Union externally in accordance with the Treaties, Van Rompuy stated.