The Barcelona youngster will spend the rest of the season at the Amsterdam ArenA as he looks to recover his fitness after missing most of the last year through injury
The 21-year-old is yet to make a first-team appearance for the Catalans this season after picking up a long-term knee injury.
And Cuenca, who has won Spain caps at Under-21 and U23 level, will now spend the rest of the season at the Amsterdam ArenA as he looks to build up his fitness once more.
"Ajax have reached an agreement with Isaac Cuenca," a statement on their official website confirmed. "The loan commences immediately and will run for five months, until June 30, 2012."
Ajax boss Frank de Boer added that he was delighted with Cuenca's arrival, saying: "I'm very happy with him. He's a more than welcome addition to our team.
"We're still competitive in three [competitions] and a player of the caliber of Cuenca is always useful. He is a very smart player and fast, he can play on the left and right wing, and besides that he's a very good football player."
Cuenca, who has made 16 Liga appearances for the Blaugrana, scoring two goals in the process, added: "After I started to train with the group, I had a little relapse. But now I feel good, ready to play.
"I'm going to have minutes [to play] and test myself after so many months of being injured."