The collapse occurred around 2am local time in the Dar-es-Salam neighbourhood of the Bbessia district, on the outskirts of the city.
Six people were also seriously injured in the disaster, while rescue teams continued searching the collapsed landfill for people who may still be trapped beneath the debris.
The government said significant resources had been deployed to rescue survivors and recover the bodies.
Prime Minister Amadou Oury Bah visited the scene, where excavators were seen clearing the collapsed rubbish mound as crowds gathered to watch the rescue operation.
Authorities said measures had also been taken to provide medical treatment to the injured and assistance to people affected by the disaster.
Before the official death toll was announced, local neighbourhood leader Lancine Sylla said 18 bodies had already been recovered and taken to a morgue.
The disaster has raised concerns over the safety of people living near the landfill. In recent days, the government had ordered residents to leave the area because of fears that the site could collapse.
Opposition figure and former prime minister Cellou Dalein Diallo, who is living in exile, described the incident as a tragedy and called for a transparent investigation into its causes.
Diallo noted that authorities had planned to close the landfill on Sunday, August 23, shortly before the collapse.
Guinea is currently led by General Mamadi Doumbouya, who came to power in a 2021 coup and was elected president in December 2025.
