Already contracted to the Dragons for the 2022 season, Griffin will now coach the Red V until the end of 2023.
"We are heading in the right direction, and myself and all the great people at the club are determined to play our roles in bringing future success to the Dragons," Griffin said.
"I have thoroughly enjoyed my time so far and I'm excited by what's to come this season and beyond."
The Dragons showed promising signs in Griffin's first year in charge in 2021, finishing 11th in a season heavily impacted by NRL sanctions after Paul Vaughan's barbeque.
Griffin, who previously coached Penrith and Brisbane, will surpass 400 games as an NRL coach later this season.
In his short time at the club, the 55-year-old has overseen an impressive recruitment drive by bringing George Burgess, Moses Mbye, Moses Suli, Jaydn Su'A and Aaron Woods to the club.
He also opted not to extend the contracts of Corey Norman, Cameron McInnes and Matt Dufty.Â
"The club has undertaken a lot of change in the last 18 months and Anthony has played a positive role both on and off the field," said club chief executive Ryan Webb.
"The board and I feel Anthony is the right man to continue setting the required standards to return the Dragons to where they belong."
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