The Spanish veteran has left Villarreal for the USA's second division, becoming part of the reincarnated New York franchise.
Senna, a key member of Spain's 2008 European championship-winning side, left Villarreal after 11 seasons, with his final act helping the club gain promotion back into La Liga. The 36-year-old joins the second-tier NASL team, which is slated to begin play in August after almost 30 years since the first rendition of the club folded.
“This is a very special moment for me in joining the Cosmos, because I face a new challenge, but at the same time it has been a difficult decision to leave Villarreal after 11 seasons,” Senna said in a team statement.
Senna had been with Villarreal since 2002, and he becomes the most noteworthy signing for manager Giovanni Savarese's side, which also includes Spanish midfielder Ayoze, Japanese winger Satoru Kashiwase and former MLS products along the lines of goalkeeper Kyle Reynish, defenders Hunter Freeman, Carlos Mendes and Korey Veeder and forward Peri Marosevic.