The Juilliard String Quartet, founded as Juilliard's resident string quartet in 1946, has had 11 different members.
Eanet will join the ensemble in July 2009, when the reconstituted quartet does its first performance at the Ravinia Festival.
He also is joining the Juilliard violin faculty next fall.
"This is quite an exciting crossroads in my career and I will miss the indelible energy and inspiring leadership of James Levine, as well as all the special moments with my wonderful friends in the orchestra," Eanet said, referring to the Met's music director.
Eanet graduated from Juilliard in 1994. He studied there with Robert Mann, the quartet's founding violinist.
"It is an enormous pleasure to welcome back Nick Eanet," Juilliard President Joseph W. Polisi said. "A musician of great artistry and intellectual curiosity, he will be a significant addition to our violin faculty, as well as an individual who represents a link to a new generation of chamber musicians."
