The 21-year-old, who made 16 appearances for the Catalan club last term, has just resumed training after eight months on the sidelines with a knee injury.
A statement on ajax.nl read: "Ajax have reached an agreement for the loan of Isaac Cuenca. The deal commences immediately and will run for five months, until June 30, 2013. The winger is leased from Barcelona."
Cuenca, a former Spain Under-21 and Under-23 international, was quoted as saying on Catalunya Radio: "If I had stayed at Barca, I would only have played league games at the end, after everything had been decided.
"I leave to get playing time, and to test myself, after having been injured for such a long time."