Maurane, real name Claudine Luypaerts, was found dead at home in Brussels around 8:00pm (1800 GMT) on Monday, according to the Belgian federal prosecutor’s office.
It said it had begun an investigation but that foul play was not suspected.
Maurane shot to fame in the late 1980s in the sci-fi rock opera “Starmania” and had a string of French-language hits before putting her career on hold in 2015 because of problems with her vocal cords, according to Belgian news agency Belga.
She announced a return to performing last week and took to the stage at an open-air festival in Brussels at the weekend, singing hits by legendary mournful Belgian crooner Jacques Brel.
“A true artist left us tonight — Maurane, an extraordinary singer, an inspiring voice, an endearing character,” Belgian Prime Minister Charles Michel tweeted.
French musician Catherine Lara told Europe 1 radio she was “devastated” by the death of her friend of 40 years, saying she had seemed tired when they last met three weeks ago.
“But she talked about the future, she told me she was preparing an album of Jacques Brel songs, that she was singing again,” Lara said.
Maurane released 11 albums in a recording career that began in 1980 and had been preparing to tour next year after the new Brel album which was due in the autumn to commemorate the 40th anniversary of his death.
“On the album front, things are going well, with 14 first takes recorded… a first single should be out in the summer,” Maurane wrote on Facebook just days before her death.
A spokesman for the prosecutor’s office told AFP they were waiting for an initial report on the death before deciding whether an autopsy was needed.
“There was no intervention by a third party,” the spokesman said, ruling out any criminal involvement.