Izzo will head to Gosford in a bid for regular game time after seven A-League appearances - and an FFA Cup appearance - for the Reds during three seasons playing second fiddle to Eugene Galekovic.
“I want to firstly say thank you to the club for allowing me to pursue this opportunity," Izzo said.
"It was a tough decision to leave this amazing club and especially the environment within the change rooms, but I know it’s the right one."
The Campbelltown City product is thrilled to have another chance at an A-League club.
"Very exciting times for me, it’s going to be a new experience for me," Izzo, an Australian Institute of Sport graduate, said.
"My agent gave me a call saying that there was an opportunity to come to the Mariners and seeing the past success they’ve had here with goalkeepers I thought it would be a great opportunity for me to grow as a player and even a person."
The 12-times Young Socceroos shot-stopper will fill the goalkeeping spot vacated by gloveman Matthew Nash, who stepped up to coaching duties after John Crawley's departure to Sydney FC, but is expected to start his tenure in Gosford as Liam Reddy's understudy.
"By watching games last year you can tell he’s [Liam Reddy] a massive character in the group so I’m sure working with him will be a great experience for me," Izzo said.
"I want to train the best I can to give the coach a headache and that can only be a good thing for the team."
