In 1985 he became a civil servant at the European Commission; first as an advisor, then as head of the administrative unit of the Directorate-General for Economic and Financial Affairs.

Subsequent positions include Cabinet Head to Commissioner Pavel Telička and Deputy Cabinet Head for the President of the European Commission José Manuel Barroso (2004 until 2006)[3] and Deputy Secretary-General (2006 until 2010).

[4] After being the Director-General of the Directorate-General for Competition from 2010 until 2015, he became Secretary-General of the European Commission on 1 September 2015, a position he held until 1 March 2018.

In 2019 he took a position as an international policy advisor for the American law firm Arnold & Porter.

[6][7] Italianer has published more than 50 articles and 3 books about the Economic and Monetary Union of the European Union, integration economics, labour, energy, macroeconomics and international trade.