The former Tottenham Hotspur player suffered a fractured skull during a clash of heads with Chelsea defender Gary Cahill in January 2017.
Mason immediately underwent surgery and has been nursing his way back to health for more than a year.
The midfielder had hoped to return to action in 2018, but now he has decided to walk away from the sport due to the risks involved.
In a statement, 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."
A statement from Hull read: "It is with deep regret that the club has to announce that, following the head injury suffered on January 22, 2017, Ryan Mason is to retire from football with immediate effect.
"Ryan has sought the guidance of numerous world renowned neurologists and neurosurgeons 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."
Mason began his career at Tottenham, but failed to secure a regular spot in the team following eight loan spells, and as a result left the club to join Hull in 2016.
Read the midfielder's statement in full here.