After missing all of last season with a shoulder injury suffered during a scrimmage last September, the 33-year-old veteran is already off to a better preseason.
The announcement was made during a news conference with Islanders team owner Charles Wang and general manager Garth Snow Wednesay at Nassau Coliseum.
"It's truly an honor to be named captain of such a historic franchise with a rich history," Streis said in a team-issued release. "To follow in the footsteps of so many legendary leaders that represented the Islanders is a role I am excited to fill. It is a privilege to be considered one of the leaders of this team and I'm committed to taking this team to the next level."
Doug Weight was the Islanders' captain for two seasons before retiring from the game in May.
"Throughout his three seasons with the Islanders, Mark has been a steadying presence in our dressing room," Snow said in the statement. "He is constantly pushing himself to be the very best and demands the same from his teammates. Mark is a leader both on and off the ice and we are pleased to name him the 13th team captain in Islanders history."
Katie Strang covers the NHL for ESPNNewYork.com.