The 70-year-old had always denied the accusations, made by a young French actress last year.
The prosecutor's office said the investigators were not able to stand up the allegations.
Mr Depardieu is one of France's most recognisable actors, and has starred in films such as Cyrano de Bergerac and Jean de Florette.
The accuser claimed the alleged crimes had occurred last August in one of Mr Depardieu's Paris residences when she was 22 years old, French media reported at the time.
When the allegations emerged, Mr Depardieu's lawyer, Hervé Temime, said the actor was "shaken" and that the claims went against "everything [the actor] is and respects".
In a statement, the prosecutor's office said: "A number of investigations undertaken as part of this procedure have not enabled us to characterise the crimes alleged in all of their individual parts."
Able to combine bearish physicality with emotional delicacy on screen, Mr Depardieu has acted in some 170 films, getting his big break in 1973 with Les Valseuses (Going Places).
He won the best actor award for Cyrano at Cannes in 1990, and was nominated for an Oscar for the same role.
Green Card, an English-language comedy made the same year, brought him further acclaim outside the French-speaking world.
Off-screen, he has made headlines in recent years for attacking French tax laws, moving to Belgium in protest and later developing close ties to Vladimir Putin's Russia.