The 26-year-old scored just one goal in 2011-12, but maintains that he is ready to return to his best, while also claiming that les Phoceens' 10th-placed finish was "shameful"
Gignac, who topped the Ligue 1 goalscoring chart in 2008-09 with Toulouse, joined les Phoceens in 2010 for £14 million.
Since then, the 26-year-old has endured a turbulent time at Stade Velodrome both on and off the pitch, with rumours of a bust-up with former coach Didier Deschamps adding to weight and fitness issues.
Nevertheless, the France international remains adamant that he will be back to his best this season, but conceded that this is his last chance to prove that he still is a goalscorer.
"These last two seasons have been really tough for me with injuries and poor performances. Even though I had a brief return to form in January 2011, what I'm aiming for is to be consistent over an entire season," Gignac told the club's official website.
"I know that I have a lot to prove and to make up to the club and the fans. OM made a huge effort to sign me, and now it's up to me to prove myself and repay their investment.
"It was infuriating to be sidelined for practically a whole season, training separately form the team, watching your team-mates winning and enjoying playing.
"But it made me stronger and I have set myself the challenge of proving that I am still the striker I once was.
"I'm full of desire to succeed and to win. This year is my first full pre-season without injury in three seasons, which is important for the season that follows.
"I know this is my last chance and I'm ready to give everything I've got and show my best qualities."
On Marseille's season objectives, Gignac declared that the team must live up to the institution's status.
"There is also a huge challenge facing the team as a whole, because finishing in tenth place last season was shameful for a side like OM.
"You have to tell it like it is, and we know we need to do better. This is a legendary club and it's very important that we have a huge season and live up to what is expected of OM players."
Gignac has so far played in pre-season friendlies against FC Sion and Benfica, with the new Ligue 1 season getting underway on August 10.