Bernard Savage, who is a key figure in the European External Action Service, made the comment in an article published today on the NewEurope.eu website.
He said: "We believe in democracy and that the Scottish people have the right to decide for themselves if they wish to remain in Britain or become independent."
Mr Savage was highly critical of the outgoing President Jose Manuel Barosso's claims and added: "Spain will not vote to remove our fishing grounds from the EU's biggest and best fleet."
And he concluded: "Mr Salmond is winning the argument in an initially hesitant Scotland and he will surely persuade Europe of the logic and benefits of the full participation in the EU of one of the continent's oldest nations."
Christina McKelvie MSP, convener of Holyrood's European and External Affairs Committee, said: "This is a very welcome common sense contribution from a man who has worked in the EU for nearly quarter of a century and understands the realities of what is in Scotland and Europe's best interests after a Yes vote.
"It follows on from Alex Salmond's keynote speech in Bruges where the First Minister outlined the huge contribution Scotland makes to the European Union.
"Scotland's has vast natural resources, rich fishing waters and cultural and social ties which place us at the very heart of the EU.
"People in Scotland want to play an active, engaged role in the EU and the only way that is possible is with a Yes vote for an independent Scotland in next year's referendum.
"The biggest source of uncertainty on Scotland's future is coming from the Westminster parties dancing to UKIP's tune - and threatening to rip us out of the EU.
"With a Yes vote in September's referendum, Scotland will gain the right to speak with our own voice in Europe and ensure that the needs of people in Scotland are always heard in EU negotiations."