The Hull midfielder suffered a fractured skull in January 2017 after clashing heads with Chelsea defender Gary Cahill.
Mason underwent lifesaving surgery after the game during which doctors inserted 14 metal plates and 42 staples into his skull after he suffered a bleed on the brain.
And despite being desperate to play again, the ex-Tottenham star has admitted defeat in his battle at the age of just 26.
In a statement released on Tuesday morning, Mason said: “I can confirm that following specialist medical advice I am having to retire from playing professional football.
“I have worked tirelessly in order to be able to return to the pitch. Unfortunately, having taken expert medical advice I now have no option but to retire due to the risks involved given the nature of my injury.
“I am and always will be eternally grateful for the incredible network of people around me who have helped me to recover from what was a life-threatening injury in January 2017.
“Thank you to my amazing fiancé, Rachel, who has been by my side and lived every single day with me since the injury, helping to give me the strength I’ve needed no matter how tough things got. We are so lucky to have now become the proud parents of our perfect baby boy George.
Ryan Mason has retired from professional football
“To my Mum, Dad, sisters, and all of my family and close friends, thank you for everything. Despite how tough it’s been and the challenges I’ve faced along the way you’ve all been there supporting me and words will never truly do justice to how grateful I am for your love and support.
“I would like to thank everyone at Hull City, especially The Doc Mark Waller and all of the medical team for helping me to recover. Thank you to the Chairman and the board for being so patient with my recovery and sticking by me.
“There are too many names to mention when it comes to talking about Tottenham Hotspur but I would like to say a special thank you to John McDermott, the Gaffer and everybody at Spurs for helping me to achieve my dreams.
“I am so proud to have come through the ranks to play for my club, the club I love. To have had the honour of captaining the team fills me with immense pride. Thank you to all of my teammates over the years, there are too many to mention, it’s been a privilege to play alongside you all.
“Finally, representing my country is an honour that nobody can ever take away from me and something that I am so proud to have achieved.
“I’m retiring from the game with my head held high having done everything in my power over these past 13 months to have given myself every opportunity to return to the pitch.
Ryan Mason suffered the horrific injury after clashing with Gary Cahill
“I feel content knowing that I dedicated my life to be able to play football at the highest level, hard work really does pay off!
“I love the game, I always will and I am excited to see where football will take me next.”
A Hull statement released at the same time read: “It is with deep regret that the Club has to announce that, following the head injury suffered on 22nd January 2017, Ryan Mason is to retire from football with immediate effect.
“Ryan has sought the guidance of numerous world renowned neurologists and neuro surgeons who have all advised that a return to competitive football is not advised.
“Ryan would like to put on record his thanks to all at the Club who have aided his recovery to this point and he his is indebted to them for their support and compassion over the past 12 months.”