Gasnier, 29, says he feels the time is right to call time on a career that has seen him make 166 appearances from the Dragons since making his debut for the club in 2000.
He also spent two years in France playing rugby union with Stade Francais.
“I just feel that the time is right and this decision is not something that I have taken lightly, “said Gasnier. “It is something that I have considered for a number of months.
“I have discussed the possibility with Peter Doust for some months now and I was conscious of making a decision early enough to enable to Club to plan the playing roster for the future seasons.
“I feel very fortunate with what rugby league has provided me and I am very satisfied with my achievements.
“I have always said that I don’t want to hang around for too long and I want to finish on my terms.
“Rugby League and the Dragons have been great to me, I couldn’t have asked for a better career path and I will be forever grateful to the club for everything that they have done for me since I was a junior,” added Gasnier.
Dragons Chief Peter Doust thanked Gasnier for his efforts.
“Mark is a quality player and more importantly a quality person who has contributed significantly to our club both on and off the field,” said Doust.
“He is a local junior who has achieved everything there is to achieve in the game and whilst we would love him to stay on, we respect and understand his decision”.