The move reunited Reyna, 33, with Bruce Arena, the Red Bulls coach who led the U.S. national team part of the time Reyna was on the U.S. squad.
"I am pleased that Claudio has agreed to sign with our club," Arena said. "Claudio is a proven player at the highest levels in the game and his experience and leadership skills will improve our team. I'm excited to have him as a member of the Red Bulls."
Reyna is a native of Springfield, N.J., and played for Arena while at the University of Virginia. He played professionally in Wolfsburg, Bayer Levekusen, in Scotland and, for the last four seasons, with Manchester City.
He is best known for his performance in the 2002 World Cup, where the United States advanced all the way to the quarterfinals. Reyna earned a spot on the FIFA World Cup All-Star First Team.