Quebec Superior Court Justice Francois Huot said a life sentence with eligibility for parole between 35 and 42 years into the sentence was appropriate, and rejected calls by prosecutors to impose the harshest sentence handed down since Canada eliminated the death penalty.
"The US Supreme Court would not find a 150-year [term] cruel and unusual punishment", Huot said earlier in the day, but added "punishment should not be vengeance".
While he did not strike down the section, he rewrote it to give himself the discretion to deliver consecutive life sentences that are not in blocks of 25 years, as had been the case.
Bissonnette, now 29, pleaded guilty last March to six charges of first-degree murder and six of attempted murder.
"This was a very serious attack in a place of worship", he said. His sentencing is ongoing in a Quebec courtroom today.
On Friday, lawyers for both the Crown and defence said they would study the decision before deciding whether to appeal the sentence.
The justice said that in the years leading up to the shooting, Bissonnette increasingly drank alcohol and experienced anxiety, depression, and suicidal thoughts.
Huot noted that witnesses at his sentencing hearing testified that he had been severely bullied in school, had a documented history of mental health problems and lacked empathy.
A university student at the time of the shooting, Bissonnette was seduced by nationalist and supremacist ideologies into committing this "unjustified and deadly" massacre, Huot said.
As the 246-page verdict was read over six hours, Bissonnette sat quietly in the courtroom, gazing at his feet while his parents and several friends and family of the victims wiped tears from their eyes.
Bissonnette also told a psychiatrist that he regretted not killing more people.
Shortly after his arrest, Bissonnette told police that the attack was motivated by immigration in Canada.
On the other hand, the judge said, Bissonnette had no previous criminal record, he pleaded guilty and he expressed remorse.
Huot agreed with the prosecution that Bissonnette's actions were exceptionally callous.
Following hearings past year, the sentence was expected to be handed down in October, but the judge delayed it to have more time to ponder his decision. More than 50 people were at the Quebec Islamic Cultural Centre in January 2017 when he began shooting during evening prayers.