The teen was caught in Green Green.
Cops policing the area also seized knives from four people two weeks ago, a meeting heard.
Police Scotland Inspector Stevie Kinvig said drug dealing has allegedly been taking place in the east end park.
Inspector Stevie Kinvig told the Calton Area Partnership meeting on Wednesday that a 15-year-old was caught with a blade and 10 bags of heroin last weekend.
The meeting heard youths have been flocking to Glasgow Green.
Describing the park as particularly “problematic,” Inspector Kinvig said: “It is particularly concerning as it is bringing together kids across the west of scotland.”
He pointed out teens have been heading to the green space from Irvine, Dumbarton East Kilbride, Livingston and elsewhere.
Inspector Kinvig said: “They are all gravitating towards Glasgow Green because they feel in comparison to Kelvingrove Park it is relatively unpoliced. That is certainly not the case.”
The Violence Reduction Unit have also been helping with the policing.
Inspector Kinvig pointed out “on a positive side “ the youths were not “gathering to fight each other.”
He added: “Sometimes on a wet Saturday evening there are about 70 kids in Glasgow Green.”
We reported how many youths have stopped heading to Kelvingrove Park after police confiscated all alcohol.
Complaints about anti-social behaviour are now down after a a police crackdown in the west end park.
Police Scotland been running an operation since April with Glasgow City Council to deal with crowds.
A Police Scotland spokesperson said after the meeting: “The 15-year-old was male and he was taken home and charged in front of his parents. He will be reported to the Scottish Children’s Reporters Administration.”