Fritzl's lawyer, Rudolf Mayer, said outside the court after the verdict: "I would say that the verdict was a logical consequence of a confession.
"Of course if you have 3,000 cases of rape and 24 years of being kept in a cellar, it is evident that there can only be a punishment or verdict like this one."
Court officials describe the details of Fritzl's life sentence
The life sentence was handed down for the murder by neglect of one of the children, who died soon after birth.
The jury unanimously accepted prosecutors' arguments that the child could have survived if it had received medical care denied by Fritzl.
The defendant first denied murder and enslavement but changed his plea to guilty after seeing testimony from his daughter.
The verdict is final and irreversible, as neither the defence nor the prosecution is contesting it.
The BBC's Bethany Bell at the court says there has been a huge amount of media interest in the trial, and its twists and turns have been enormous.
At the time of the first details of this case, no-one could grasp the extent of this man's crimes, she says, and Austria still has to come to terms with it.
Court officials said Fritzl would initially return to St Poelten jail, where he has been held in custody. Justice Ministry spokeswoman Katharina Swoboda told AFP news agency that he would remain there in the coming weeks.
I regret from the bottom of my heart what I've done to my family
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