Porter, who made his A-League debut in round 12 of the 2006/07 season, made 90 appearances for Mariners in his six years at the club.
'It’s been a tough decision to make to have to retire from the game, but at the end of the day I did the injury nearly two years ago now and in that time it’s been extremely frustrating trying to come back and having setbacks," Porter said.
'The way I look at is that I’ve been a professional at the club for close to seven years and there are a lot of young kids and a lot of people out there that would give up a lot to have done that."
'I’m very proud of what I’ve achieved at this club. To have been here from basically day one and to have seen the growth of the club both on the pitch, and building the supporter base and the community support has been unbelievable."
While injury has cruelled Porter’s chances of prolonging his playing days, the former Australian Institute of Sport scholar acknowledged the time had come to listen to his body.
Porter is looking at a move into coaching.
'Even when I was fully fit I had dreams that when I retired I was going to get into coaching," he said. 'I guess it’s just come a little earlier than I expected."
'Everyone has goals and dreams growing up as to what they want to achieve in football, I still have those dreams and goals.
"I guess now I am standing on a touchline instead of out there with the boots on.
'I’ve spoken to Arnie (Mariners coach Graham Arnold) and he’s more than happy to have me in, so I’m going to be in and around the squad.
"I’ll be like a sponge, soaking in information and I guess looking at things at a different perspective."
Arnold said it is a 'tragedy’ for a 25-year-old to have to call time on his career because of injury.
'Brad has always been highly rated at the Mariners, and unfortunately due to injury over the two years that I’ve been here, I probably didn’t get to see the best of Brad," Arnold said.
'When I first came here Brad was a young player that I was looking forward to working with.
"We wish Brad as a guy who is a Mariner through and through the best for the future."
Mariners General Manager – Football, Lawrie McKinna, signed Porter to his first professional contract and today echoed Arnold’s sentiment.
'When we first signed Brad he was a young, quiet boy and in the last five or six years he has grown to become an important member of the Mariners family," McKinna said.
'Brad always gave 100 per cent in training and on the park and I believe his strength was his fitness, which made him adaptable to many positions."