Abel Xavier has agreed an 18-month deal to join former England captain David Beckham at Major League Soccer side LA Galaxy after leaving Middlesbrough.
The 34-year-old former Everton and Liverpool defender will be eligible to play for LA Galaxy from 15 June.
Galaxy president and general manager Alexi Lalas said: "Abel brings immense experience and a wonderful personality to our team.
"He's a great defender and we are excited that he is coming to LA."
"People of his quality are not often available for us to sign, so we are really happy that he is going to join us"
Xavier said: "I'd like to thank Alexi Lalas, Frank Yallop and MLS for this opportunity.
"Soccer is my life and I'm excited to continue my career in LA. Soccer in the United States continues to grow and I'm proud to be a part of it.
"I'm coming to win. With the great team and wonderful fans at LA Galaxy everything is possible. I bring heart, hunger, desire and passion. This is me today, tomorrow, and always."
Galaxy head coach Yallop added: "This is a terrific signing for us and he will bring so much experience, leadership and ability to the team.
"People of his quality are not often available for us to sign, so we are really happy that he is going to join us."
Xavier had a turbulent spell at the Riverside after moving on transfer deadline day in August 2005.
In October that year he was banned from playing football for 12 months after failing a drugs test.
He rejoined Middlesbrough in November 2006 after serving the ban and made 20 appearances in 2006-07.
The Mozambique-born player has 20 caps for Portugal, scoring twice.
He will line up with Real Madrid's former England captain Beckham at LA Galaxy.
Midfielder Beckham is set to move to the United States club in July.