The teenager was found on a towpath near Burrows Court, Eldonian Village, in the Vauxhall area of the city, by a member of the public at about 23:10 GMT on Sunday.
He was taken to the Royal Liverpool University Hospital, where he died a short while later, police said.
Merseyside Police has not commented on reports that a “gang fight” had been arranged in the area.
The boy’s next of kin have been informed of his death. A murder investigation has been launched and forensic examinations of the scene are being carried out.
One resident of Eldonian Village, who knew the victim and would only identify himself as Dylan, said the teenager lived in the area.
“I woke up this morning and I’d got a text off my mate saying [he] was dead,” he said.
“[He was] a very kind kid, who would do anything for you.”
Officers said they were trying to establish a motive for the shooting and high visibility patrols have been stepped up in the area to reassure the public. House-to-house inquiries are under way.