Calling himself a crusader against a tide of Islam in a rambling 1,500-page online manifesto, the 32-year-old mass murderer wants the opportunity to explain actions he deemed "atrocious, but necessary".
Lawyer Geir Lippestad said his client had admitted to Friday's shootings at a Labor youth camp and a bomb that killed seven people in Oslo's government district, but that he denies any criminal guilt.
"He has been politically active and found out himself that he did not succeed with usual political tools and so resorted to violence," Lippestad told TV2 news.
"I await a medical assessment of him," he said.
That Breivik deliberately surrendered to police when finally confronted on the tiny island of Utoeya after cold bloodily gunning down 86 youngsters underlines his desire to grab a public platform to deliver his radical thoughts.
In other instances of gunmen going on killing sprees the perpetrators often commit suicide when the police arrive or actively provoke officers to shoot them dead.
It was not clear how long Breivik will have to talk in court since the hearing will be about custody and he will not be required to enter a guilty or innocent plea.
Friday's shooting spree lasted for around 90 minutes before Breivik surrendered to police, who immediately arrested him. Police said on Sunday that Breivik had ammunition left over.
"Breivik is being held at Oslo's police headquarters," Al Jazeera's Harry Smith, reporting from Norway's capital, said. "On Monday, he will be transferred across town for an appearance at the city's criminal court."
"His lawyer has said on that occasion [Breivik] will explain fully what he's done, and more importantly, why he did it."
Witnesses described scenes of horror among the more than 500 people attending the youth camp. Some who tried to swim to safety were even shot in the water.
The chief surgeon at a hospital treating victims of Norway's camp massacre says the killer used special bullets designed to disintegrate inside the body and cause maximum internal damage.
And ballistics experts say so-called dum-dum bullets also are lighter in weight, can be fired with greater accuracy over varying distances and are commonly are used by air marshals and hunters of small animals.
Sveinung Sponheim, the acting police commissioner, said that all the dead had now been removed from the island and "taken to the coroner's morgue where the autopsies will be carried out".
During weekend interrogation, Breivik told police that his attacks were "cruel" but "necessary".
While he "admitted responsibility", police said, his lawyer Geir Lippestad said he was not accepting "criminal responsibility", and that his client felt he had done "nothing reprehensible".
The attacks have caused outrage in Norway amid calls for the reinstatement of the death penalty, given the maximum prison sentence the perpetrator can face is 21 years' imprisonment.
Police have not ruled out the involvement of a second gunman, and on Sunday they detained several people in a swoop on an Oslo property thought to be connected to the attacks. They were released shortly afterwards and no explosives were found.