Swedish Prime Minister Fredrik Reinfeldt, who chaired the meeting, said it took time to consult with all of his 26 EU colleagues.
"But it's very important to show that everyone has a say, that this is the Europe of 27, that everyone was actually in on this decision, and this also showed tonight when we unanimously could support both of these candidates," Reinfeldt said.
Belgian Prime Minister Herman Van Rompuy, 62, has been in charge of the Belgian coalition government for less than one year. His tenure has seen a calming of the often turmoil-stricken Belgian government.
Catherine Ashton, 53 and formally a Baroness, has been a close ally of British Prime Minister Gordon Brown since joining the UK Labour Party. Ashton had held a number of mid-level positions in the UK government related to education, justice and human rights before being promoted to the position of EU trade commissioner a year ago.