The irony of the honour being bestowed in the midst of one of the EU's worst crises and at a time of deep rifts between major member states was not lost on anyone, including the EU's biggest supporters.
Cynics said the award is less about celebrating its legacy of peace but more about delivering positive public relations when the EU needs it most.
The Norwegian committee awarding the prize said the EU would be its next recipient in recognition of its six decades of contributions "to the advancement of peace and reconciliation, democracy and human rights in Europe".
Its citation focused on the EU's historical role in the aftermath of the Second World War, but many observers are astonished by the decision, given the deep divisions that have emerged in response to the economic crisis of recent years.
The leader of Britain's Conservative Euro MPs Martin Callanan said the announcement came "a little late for an April fools' joke".
He said: "Twenty years ago this prize would have been sycophantic, but maybe more justified. Today it is downright out of touch. Presumably this prize is for the peace and harmony on the streets of Athens and Madrid. The EU's policies have exacerbated the fallout of the financial crisis and led to social unrest that we haven't seen for a generation."
The decision came in the week when German Chancellor Angela Merkel faced "Nazi" salutes from angry Greek demonstrators when she visited strife-torn Athens to reject claims the country was, economically at least, under German control once again. The news reminded everyone the Finance Minister of Poland warned MEPs during a European Parliament debate last year that the economic and political crises could lead to war within 10 years.
Choosing to give the entire EU the Nobel Peace Prize at such a time only diminishes the point of the award, Mr Callanan claimed.
"The Nobel Peace Prize was devalued when it was given to newly elected Barack Obama. By giving the prize to the EU, the Nobel committee has undermined the excellent work of the other, deserving winners of this prize. The Nobel committee is a little late for an April fools' joke."
But the German President of the European Parliament, Martin Schulz welcomed the acknowledgement of the EU's role in peace. "The EU has reunified the continent through peaceful means and brought arch-enemies together. This historic act of reunification has been rightfully recognised," he said.
Nobel committee chairman Thorbjoern Jagland said: "The Norwegian Nobel committee wishes to focus on what it sees as the EU's most important result: the successful struggle for peace and reconciliation and for democracy and human rights. The stabilising part played by the EU has helped to transform most of Europe from a continent of war to a continent of peace."
However, Ukip leader Nigel Farage, whose party campaigns for the UK to leave the EU, said: "You only have to open your eyes to see the increasing violence and division within the EU which is caused by the euro project.
"Spain is on the verge of a bail-out, with senior military figures warning the army may have to intervene in Catalonia. In Greece, people are starving and abandoning their children through desperate poverty and never a week goes by that we don't see riots and protests. Rather than bring peace and harmony, the EU will cause insurgency and violence."
