Greiss became a free agent in July 2013 and subsequently signed a one-year contract with the Phoenix Coyotes. In his only season with Phoenix, he played in 25 games, posting a 2.25 goals against average (GAA) and .920 save percentage. At the end of the 2013–14 season, he was not re-signed by the Coyotes, whereupon he signed a one-year, $1 million contract as an unrestricted free agent with the Pittsburgh Penguins on 1 July 2014. After the 2014–15 season in which he appeared in 20 games for the Penguins, Greiss once again switched teams as a free agent, signing with the New York Islanders on a two-year, $3 million contract. In March 2016, Jaroslav Halák, the Islanders' starting goaltender, suffered a lower-body injury sidelining him six weeks, leaving Greiss as the team's temporary starter.