Chever Ashley will not be eligible for parole for 15 years.
Spencer, 23, was in a Scarborough recording studio in the early hours of Jan 21, 2012 with some friends and Ashley and his co-accused Samuel Paul, also known as rapper Sammy G.
According to an agreed-upon statement of facts, Ashley and Paul pulled out guns and ordered Spencer and his friends to lie on the ground before robbing them.
At one point Ashley shot Spencer in the chest.
The judge called the slaying a "callous and cowardly execution of a defenceless man" but gave Ashley credit for pleading guilty.
Salt in the wound
Spencer's family say justice was done — but with no thanks to his friends who took him to Scarborough General Hospital but refused to co-operate with the police investigation.
A Canada-wide warrant was issued for LaPrincia Palmer, a friend and key witness to the shooting, who eventually turned herself into police.
"They didn't do anything to help this case," said Susan Spencer. "Not a thing other than obstruct justice and throw us into the wrong direction."
"It was salt in the wound."
The family says it's now up to them to raise the victim's six-year-old daughter.
"She doesn't understand. She just wants to know why the bad guy did it and I don't know how to explain. I don't think anyone can explain that," Spencer said.
Paul has pleaded guilty to robbery with a firearm, breaching an order not to have guns and violating his bail conditions. He will be sentenced next week.