The outgoing European Parliament President is the first Irish winner of the Charlemagne Prize. He received the award at a ceremony in Aachen, Germany.
Previous recipients include EU founding father Jean Monnet, Winston Churchill, Henry Kissinger, Edward Heath, Tony Blair, and Bill Clinton.
This year, for the first time, the prize was shared. Mr Cox is the joint recipient with the Pope, who took part in a separate ceremony in Rome in March.
The Charlemagne Prize was launched by Aachen in 1949 when the city was still in ruins in the wake of the World War II.
The prize is named after the Aachen-born 8th century Emperor Charlemagne, who was known as a founder of Western culture.
Recipients are recognised for "contributions fostering mutual understanding among European peoples".
Yesterday's declaration by the City of Aachen said that the Charlemagne Prize Board was honouring the foremost representative of the only directly elected EU institution, which had "decisively added to the quality and dynamism of... enlargement".
The citation went on: "This liberal Irishman is possessor of three key qualities: transparency, a popular touch and a pragmatic approach to politics."
Mr Cox became an MEP in 1989, was elected to the leadership of the Liberal Democrats in the European Parliament in 1998 and was voted President in 2002.
Last month he announced he would not be standing in the Euro elections in June effectively clearing the way for a stab at becoming Ireland's next EU Commissioner, or even President of the European Commission.
His ceremonial speech yesterday insisted that a new constitutional treaty due to be approved next month would "permit us to pass from a decade and more of endless introspection on issues of institutional design and process to real political issues of substance".
He added: "We must explain to people about our commitment to the promotion of human rights and our respect for the rule of law. In our troubled world of today we must insist that prisoners of war have full rights under the Geneva Convention."