The Minister for Finance, Mr McCreevy, has been appointed the EU Internal Market Commissioner by the European Commission president Mr Jose Manuel Barroso.
Mr McCreevy said he was particularly pleased to have been allocated the Internal Market portfolio which, he said, was a "very significant portfolio in the enlarged Europe".
The Minister said he would work to expand on the progress made since the Single Market was established in 1993.
He said he was looking forward to the challenge that his new post would present and said that he will work with his new Commission colleagues to create the conditions to enable the enlarged European Union to meet its potential of becoming the most dynamic economic region in the world.
He identified the area of services as one of particular importance and added that the elimination of barriers in this area would contribute significantly to the creation of a genuine single market.
The Internal Market Commissioner is tasked with developing and overseeing internal market, competitiveness and company law issues and is also responsible for accounting and auditing policy issues.
Mr Barroso unveiled his new team at a press conference in Brussels. "We must seek new high tech means to foster growth while maintaining our industrial base," he said. "Only by creating new jobs can we build on our successful European social model."
Mr Barroso said one of his main purposes was to communicate the European ideal more effectively to EU citizens, following the low turnout at this year's European parliament elections - and he has appointed a new vice-president to achieve that.
France's Mr Jacques Barrot, a close ally of French President Jacques Chirac, was named vice-president in charge of transport, while Britain's Mr Peter Mandelson, takes over the trade portfolio.
But arguably the commission's most powerful post - which rules on mergers, antitrust cases and illegal state subsidies to business - went to former Dutch Transport Minister Neelie Kroes.
Mr Barroso had been Portugal's prime minister for barely two years when his fellow leaders chose him in June to succeed Mr Romano Prodi of Italy, whose term as European Commission president expires at the end of October.
Since his July 22nd confirmation by the European Parliament, Mr Barroso has been meeting the 24 commissioners selected by EU countries to join him in Brussels, as well as fielding calls from capitals lobbying for top spots.
Each EU country nominates one commissioner, and Mr Barroso's team will have an unusually high number of heavy-hitters: three ex-prime ministers, five foreign ministers and three finance ministers.
After confirmation hearings in the European Parliament, the new commission starts its five-year term on November 1st. It will be the first with 25 members, marking the entry of ten new countries to the EU last May.