The club is yet to make an announcement on his imminent arrival.
It is being reported that the Dragons have offered him the job as they overhaul their coaching staff following a disappointing 2019 season.
The 53-year old was deregistered at the end of last season by the NRL following the Sharks’ salary cap scandal, but has been cleared to return to coaching for the next two seasons in an assistant role.
St George’s review, which was conducted by former Panthers boss Phil Gould, emphasised the need to pair coach Paul McGregor with an experienced head, who remains under contract for the next two seasons.
Flanagan is expected to accept the role and take over from Ben Hornby.