The brothers, aged 21 and 23, are charged with killing the man in their home in Holmlia in Oslo and then taking his body out to a wooded area and laying it in a ditch.
In the indictment, the prosecution reported that the two brothers repeatedly struck the man across the face before cutting his throat with a pizza cutter, or a knife, or possibly both.
The two men are pleading guilty to the murder, which they claim took place in February when they were in a state of intoxication.
They did nothing to hide the body once they had placed it in the ditch, and phoned the police themselves to report the murder and direct officers to the body.
“He profusely regrets what happened and is looking forward to receiving his punishment after the case comes to court,” the elder brother's lawyer, Ole Petter Drevland, said.
Odd Ivar Grøn, from the law firm Lippestad, is representing relatives of the victim.
“It has been a tough time for the family and it has been difficult for both his parents and his younger siblings,” Grøn told Norway's Dagbladet.