Monique De Wael, who adopted the pseudonym Misha Defonseca, also admitted that she was not Jewish.
Her revelations came in an interview with the Belgian daily Le Soir, which said more than six million people had already seen Surviving With Wolves.
"It’s not actual reality, but it was my reality," she told Le Soir.
"It was my way of surviving… I seek forgiveness from those who feel betrayed, but I implore them to put themselves in the position of a little four-year-old girl who has lost everything, who has to survive."
The story, presented as autobiographical, tells of a little Jewish girl whose parents are arrested and deported by the Nazis in 1941.
She goes in search of them across Belgium, Germany and Poland, with only the wolves for company. The book was first published in 1997.
In reality, De Wael says her non-Jewish parents were in the resistance but were indeed deported by the Nazis.
She says she then stayed with her grandfather and was "treated badly".
"It’s true that I’ve always felt Jewish… it’s true that I’ve always created a different life for myself, a life that cut me off from my family, a life far from the people I hated," she said.
Her true story came to light after suspicions were voiced in Belgium about her tale, prompting Le Soir to seek clarifications from her.