The NSW captain, who made his debut for the Sharks in 2001, has played more the 200 games for the club and is very much the heart and soul of the perennial strugglers, who have made the finals once in the past six seasons.
Gallen flies out to the UK on Friday with the Kangaroos squad for the Four Nations, and will front a media conference at Toyota Stadium on Wednesday to announce his decision.
The good news for the club is likely to continue later this week with Todd Carney set to agree to a short-term deal.
Any contract will need to be ratified by the NRL, who need to be convinced the club has a plan to help the troubled playmaker remain on the straight and narrow.
Gallen got to know the 25-year-old well in the Australian camp during last year’s Four Nations campaign.
He’s believed to have played a big role in convincing the club to take a chance on the troubled player.