Police were called to Abbot Street, in Shawlands, in the South of the city, after they were alerted by a member of the public who noticed the weapon.
Several armed response units and officers rushed to the scene. They taped off Abbot Street and nearby Frankfort Street at around 9pm last night.
Forensic officers then began combing the area and surrounding streets.
They made the scene secure before recovering the gun.
Part of Shawlands Cross was also cordoned off and traffic was being diverted.
Shawlands residents spoke of their shock at the amount of police activity in the area.
Cameron Taylor said: "Shawlands all shut off by police. Pollokshaws Road, Frankfort Street and Abbot Street taped off. Forensic and armed response here."
Police said they were not looking for witnesses.
A police spokeswoman said: "Police were called out to Abbot Street after receiving a call from a member of the public regarding a firearm in a bin.
"Officers recovered the firearm from the bin on Abbot Street.
"Nobody was injured in the incident.
"Police are not looking for witnesses at this moment, however, inquiries are ongoing."