Five judges at the Oslo High Court were unanimous in ruling that Breivik, who killed 77 people in a bomb attack and gun rampage in 2011, was sane.
The 10-week trial of the 33-year-old terrorist ended on Friday, after he was given the maximum verdict of 21 years, which could be prolonged if he was deemed to remain a threat to society.
Breivik detonated a bomb in the center of the capital, Oslo, and went on a shooting spree at the governing Labor Party’s annual youth camp on Utoya Island on July 22, 2011. Eight people died in Oslo and 69, mostly teenagers, were killed on the island.
He earlier insisted that he was sane and refused to plead guilty by saying that he wanted to be found accountable for his actions so that his anti-Islam ideology will be taken seriously.
Prosecutors had called for him to be regarded as insane and be hospitalized in a mental hospital.
A first team of psychiatrists, appointed by court to test Breivik, disagreed on his sanity. However, the second team found that the confessed killer was not psychotic when carrying out the attacks and shooting several of the victims at the youth camp in the head.