The all-action forward – who has clocked up 78 appearances for his region – has put pen to paper on a new contract.
Director of Dragons Rugby, Dean Ryan, said: “Ollie is an outstanding talent and we are absolutely delighted he is staying with us.
“He showed earlier this season the influence he can have on games and we know he can get even better in our environment.
“We’re delighted he has chosen the Dragons as where he wants to continue to develop and achieve his ambitions.”
Griffiths, 25, is currently closing in on a playing return.
He has been a standout performer this season and Ryan believes his re-signing is a statement about retaining the best talent at Dragons.
“Signing our players of international calibre, of which we know Ollie is, is a huge part of building our squad for the future,” added Ryan.
“We want them to know this region is the right platform to get better and not accept where they are at the moment as the ceiling.
“It’s an important statement that they see that future here and we hope to have more positive news on the coming weeks.”
