Cosmos start their second life when they begin their second-tier North American Soccer League campaign on August 3 against the Fort Lauderdale Strikers and Senna is set to make his debut on that day at Hofstra University as the franchise begin their resurrection.
The 36-year-old Brazil-born midfielder, who was voted player of the tournament for Euro 2008 after helping Spain lift the trophy, was finally unveiled as a Cosmos player after weeks of speculation over the move.
It brings to an end an 11-year association with Villarreal, who clinched promotion back to the top flight in what was Senna's final act as their skipper.
“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,” said Senna.
“I want to thank Giovanni Savarese, Remy Cherin and my agents Ely Coimbra and Hector Peris for helping me make this move possible.”
“We are delighted to add Marcos Senna to the New York Cosmos,” Cosmos head coach Giovanni Savarese added.
“His reputation in the game and his achievements over his career on the field speak for themselves – he’s the type of player that makes everyone on his team better and his leadership and experience will be invaluable for us.”