Often reduced by critics to her sharp tongue and combative manner, Schwarzer has in recent years become a controversial figure even among feminists, many of whom say her approach has become outdated.
But in her autobiography published last year Schwarzer described herself as a knowledge-hungry woman who loves life, likes to celebrate and has many friends.
She started campaigning for women's rights in France in the early 1970s before returning to her native Germany. In 1975 she published her first book, The Small Difference, which propelled her to the front of the country's fledgling feminist movement.
Quotes such as this from that book: "The penis – in its flaccid condition, experts assure us, it's eight to nine centimetres; rigid it is six to eight centimetres more. And being a man is contained in this little tip?" were used by detractors to portray her as a man-hating feminist troublemaker.
Two years later she set up the magazine Emma, which led campaigns on subjects such as female genital mutilation and sexual abuse, as well as calling for gay marriage rights and paternity leave as early a the 1980s. It continues to be considered the leading German feminist magazine.
She often takes part in political talk shows, and has become a "media personality" in many respects. She was awarded the government's Order of Merit medal in 2005, cementing her position as one of Germany's leading societal figures.
Although her contribution is generally recognized as significant for women's rights in Germany, she is not universally liked or respected – and has attracted the ire of other feminists for what some criticize as her old-fashioned and inflexible attitudes.
Bascha Mika, former editor of the left-wing daily Die Tageszeitung has been publicly critical, while historian Miriam Gebhardt wrote a book about her called "Alice in No-mans-land", which described her as inflexible and a matriarch who was constantly promoting herself.
She was also accused of selling out last year for writing in the sensationalist Bild newspaper, which then still carried photos of topless women on its front page – something she had previously attacked for being misogynist. She wrote commentary on the rape trial of a famous weatherman for the paper, saying that she was writing on behalf of his victim – although he was acquitted for lack of evidence.
In interviews this week she said she would continue to fight against prostitution and pornography. She said she wanted to make it embarrassing for men, "to buy the body and soul of a woman for a few notes."
Regarding pornography, she said it was, "not about naked skin or eroticism, rather about the linking of sexual desire with the desire to humiliate, and violence."
In a birthday blog entry, Schwarzer quoted from an interview she conducted in 1978 with Simone de Beauvoir, when the French intellectual and feminist said, "Women cannot fall so far [as men when they age] because they were never on top. But the men who consider themselves important, they believe they had power and responsibility – and often do have that. When they age it is terrible. That is a real break."
Schwarzer also said how she planned to celebrate her 70th birthday: "We will dance until at least two or three in the morning. Rock 'n' Roll, what else? Because as far as I am concerned, honestly – I feel ageless. But – how do I tell the others?"