The boy's name was Jamir Frazier, his family confirmed to ABC7.
The Kankakee County coroner said an autopsy was conducted Wednesday and the boy's preliminary cause of death was drowning.
The family held a balloon release in the boy's honor Wednesday night near Beckman Park, by the docks where the boy slipped into the river.
His step-grandmother, Oshana, said Frazier was involved in youth sports and was a beloved little boy. He was described as vibrant and mighty, and he had a passion for sports and adoring love for his mother, Angel Jackson.
The mother's longing was a pain that could be heard and felt.
"He's like the best son somebody could ever have..." Jackson said. "Energetic, loving, caring. He cared so much about me. He checked on me as much as he could."
Jackson desperately fought yesterday to save her son after he slipped into the water Tuesday afternoon, but the Kankakee River's current was too strong.
The community vowed to be strong Wednesday night as dozens gathered at the place Jamir lost his life, including his fellow Kankakee Elite football teammates, to remember the bright life he brought to so many.
"When it comes to kids, we come together as a family," said Seyborn Billings, President and Athletic Director of Kankakee Elite Football and Cheerleading. "Kankakee is a family. A big family."
As the crowd let go of their balloons, they yelled, "forever Jamir," leaving behind a sea of floating stars drifting over the Kankakee River.
"Jamir ain't let you forget he was there, if he was around you, he didn't let you forget," Jackson said. "He didn't let you forget at all."
The boy's youth football team, the Kankakee Elite, will host a benefit in his honor next Monday.
The organization's president said so far the team has gathered enough money to cover the cost of his funeral, which will be held next week.