Marois proposed the idea of honouring Denis Blanchette at her meeting Thursday with outgoing Premier Jean Charest, and he agreed.
A City of Montreal spokesperson confirmed the arrangement to CBC News.
Details of the official funeral are still to be worked out.
Friends and colleagues of 48-year-old Blanchette, killed when he was hit by a bullet outside the Metropolis concert hall midway through Marois's speech, have been remembering him over the past two days.
Hundreds of people gathered in downtown Montreal on Wednesday night at the scene of the deadly election-night shooting to remember Blanchette and call for unity.
Many of them showed up again on Thursday, as the man accused of the killing had his first hearing at the Montreal courthouse.
"For us, he was a brother, a friend, someone who was with us every day of our lives. Denis was a guy who always had his heart in his hand," said Denis Bourgault, Blanchette's housemate and friend since childhood.
Sébastien Bourgault, who said Blanchette was like an uncle to him, drove with his father to Abitibi on Wednesday night to pick up the victim's four-year-old daughter and bring her to her dad's funeral.
"She was saying, 'Where is my dad? Where is my dad? My dad is dead. I'll never see him again,'" Sébastien Bourgault said. "She repeated it maybe a hundred times. I told her, the only place you'll be able to see him is if you close your eyes and look into your heart, and he'll always be there."
Bourgault said he told Blanchette's daughter that her dad died a hero, giving his life to save others from a gunman apparently intent on wreaking havoc.
One of Blanchette's colleagues said he filled in for her on Tuesday when she went to vote and pick up her daughter.
"He gave his life for $15 an hour," said Marie-Jo, who wouldn't give her last name. He was a hard worker and proud of it, she said.
Marie-Jo worked with Blanchette at Productions des Grande Bambou and described how technicians there are a close-knit group, sometimes spending 80 to 90 hours a week with each other.
"We're a family. Today, we've lost a member of our family," she said.
Man wounded in shooting remains in hospital
Despite the feelings of brotherhood at Wednesday night's vigil, a few people groaned when one of the organizers said he wanted to address them in English near the start of the gathering, which took place in front of the Metropolis, on Ste-Catherine Street.
"We are here today, united as a family, crying for what we love – Quebec," said George Stamatis, one of the organizers of the vigil.
"We are crying here today because this act does not represent any of our values.… This act does not represent democracy. This act does not represent who we are as Québécois."
Stamatis, who didn't know Blanchette, helped organize the event through social media.
Another of Blanchette's colleagues, 27-year-old Dave Courage, was injured in the shooting. He was taken to hospital with a serious bullet wound and operated on, but is now in stable condition.
The man accused of shooting Blanchette, Richard Henry Bain of La Conception, Que., appeared in court Thursday to be formally charged. He faces 16 counts, including first-degree murder, attempted murder, arson and aggravated assault.
A unidentified police official has told The Associated Press that the gunman's weapon jammed after the first shot was fired, suggesting the shooting could have been much worse.
Witnesses who spoke to La Presse newspaper said Blanchette and Courage, seeing the armed man outside the Metropolis, tried to stop him before he opened fire on them.