The team confirmed Beasley's signing on its Twitter feed Wednesday.
The 29-year-old American is coming off a season with German club Hannover 96 in which he saw little action. He also has played with Glasgow Rangers, Manchester City, PSV Eindhoven and the Chicago Fire.
Beasley has played almost a decade on the U.S. national team and was on the United States' 23-man roster for the 2010 World Cup, making one brief appearance. He also is a veteran of the 2002 and 2006 World Cups.