The defender first linked up with the Pilgrims in October.
The 26-year-old has enjoyed a productive stint at Home Park, making five appearances.
Plymouth initially moved for Griffiths' services after seeing their defensive options depleted.
With Onismor Bhasera away on international duty and Robbie Williams out injured, boss Carl Fletcher required reinforcements.
Having been suitably impressed by his new recruit, Fletcher has now opted to keep the full-back on.
Griffiths will be available up to and including a trip to Bradford City on 20th November and has been granted permission to figure in Sunday's FA Cup clash with Dorchester Town.