The 32-year-old former French international has penned a two-year deal with the Corsican outfit after agreeing to terminate the final year of his contract with Lille.
"It was sorted out in a few days," Orsoni told reporters. "We quickly found an agreement with the player and his agent, and we agreed terms with Lille too.
"As we are used to do, we didn't pay any transfer fee. Otherwise we could have not bought him."
Pedretti has 22 caps for France, the last of which came in 2005.