Mrs Kohl had suffered for several years from a serious skin disease that made her sensitive to daylight and forced her to remain indoors most of the time.
"Despair at the state of her health led her to end her life of her own free will," said the statement issued hours after Mrs Kohl's body was found early on Thursday in her home in Ludwigshafen, western Germany.
I stand by my man
Hannelore Kohl was married to modern Germany's longest-serving leader, and was by his side throughout the dramatic events following the fall of the Berlin Wall.
A tiny blonde figure next to her husband, she was once dismissed by cynics as the "Barbie of the Rhineland" for her stiff hairspray and high-collared blouses. But although shy of the limelight she helped her husband battle - in vain - to avoid election defeat by Gerhard Schroeder.
"Once you've got Kohl, you've got him for a long time," she said during the 1998 campaign.
Helmut Kohl was out of office after 16 years, and within a year he was at the centre of party funding scandal that wrecked his reputation. But Hannelore supported him.
But she said the parliamentary and criminal investigations into irregular campaign donations had left her longing for a quiet life.
The couple met when she was just 15 and he 18. They wed 12 years later, in 1960, after Mr Kohl wooed Hannelore, with, she said, more than 2,000 love letters. They had two sons.
Mrs Kohl was active in charity causes and chaired an association that helps accident victims with brain disorders to rehabilitate. A few years ago she authored a cookbook with her husband.
However, in her final years, she was rarely seen in public and had withdrawn from political life. Her skin disease prevented her from attending her younger son Peter's marriage in Turkey at the end of May.
Doctors in Germany and abroad had failed to alleviate the extremely rare ailment, the statement said.
The statement from Mr Kohl's office said she had conveyed her decision to take her life in farewell letters to her husband, her sons and friends.
Hannelore Kohl was born in the Palatinate region of western Germany, and grew up in Leipzig, where she lived until the end of WWII.
She worked as an interpreter in French and English.