Marseille complete Gignac deal
French media reported Gignac, Ligue 1 top scorer in the 2008/09 season, moved in a deal worth 18 million euros.
"I'm very proud to wear Marseille's shirt. This is a dream come true," the striker, who was born in Martigues, a town near Marseille, told reporters.
Gignac, 24, has scored four goals from 16 caps for France. He was part of the French squad during last World Cup.
Marseille turned to Gignac last week after they failed to sign Sevilla's Brazil striker Luis Fabiano.
The Provence side have also signed Loic Remy from Nice. The 23-year-old striker was cleared to play on Tuesday despite a heart problem.