The Mariners see the out-of-favour Guangzhou R&F forward as a potential turbo-boost to their top-six hopes, whilst simultaneously offering him the chance to resurrect his receding Socceroos' FIFA World Cup prospects.
The move has been spurred by the abrupt departure of Spaniard Asdrubal, and the hope is that Giannou’s Chinese Super League side, who have used the Greek-born 27-year-old sparingly over two seasons, will be release him before the season kicks off in March.
"We're doing what's possible to bring him to the Mariners and enhancing his chances of Socceroos selection," said Charlesworth, whose side sit three points off the play-off places after 17 rounds.
"He can make a big difference in attack for us, with his instinct for goals, if we're successful in bringing him here.
"We're determined to make the play-offs, and we'll do all we can to achieve that."
The Mariners, who have scored just 17 goals this season, are hoping the recent cap on foreign imports in the CSL will prove pivotal in discussions with Guangzhou R&F officials.
Giannou, who played for both Australia and Greece at youth level, was enticed into the Socceroos fold by Ange Postecoglou.
But he hasn't featured since November 2016, and remains locked on four caps without scoring.
While his strike rate in Greek's top tier has been impressive, he has struggled to flourish in China - scoring five goals in 22 league appearances in his first season, and two in seven in season two.
The crux of the proposed deal will hinge on wages, with his R&F deal worth around $2.5 million over three seasons.
And the chance for Giannou to rediscover his goal touch and impress whoever succeeds Postecoglou as Australia coach heading into Russia 2018.