Twenty teams took part in the competition on Saturday, held this year in Chateauneuf-du-Pape, famed for its distinctive red wine, near the southern city of Avignon.
Identifying wines by taste and smell alone, the Spaniards gained 140 points, squeaking past the Belgians by two points, with Sweden in third.
"It was a slight surprise we knew that the competition were very good and the level very high," a member of the Spanish team said.
The US, making their debut appearance with a five-member squad all aged in their 40s, were philosophical in defeat.
"We were confident at the start but then it became complicated," said team member Christophe Dantzenberg. "We had disagreements (over identifying wines) and often had to reach a compromise."
The 12 wines used in the competition ranged from a German Riesling, a Sauvignon from New Zealand, a Sangiovese from Italy as well as several French wines, including one from the host region.
The teams blind-tasted fine wines from around the world. They had to identify the countries of origin, the grape varieties used, the appellations and the vintages.
"There was no trap", said Philippe de Cantenac, a journalist from the French wine magazine which pioneered the event. "But some wines are not easy to identify like Croatian or Greek ones."