Benitez has been aware of the 28-year-old's talents for some time.
"We knew him before and he was always a player you monitor," Benitez said. "He was playing for Villarreal and the chairman didn't want to lose one of his best players before they were in trouble.
"But now Cazorla is doing well in a good team with a good manager. When I came to England I brought (Xabi) Alonso and one or two others and it took them time to settle down, but Spain has a very good level now and it is good for the game here.
"You can bring the best from them and combine it with the best from England."