Buenos Aires legislators have voted to remove Mayor Anibal Ibarra from office for dereliction of duty over a fire that killed 194 people in 2004.
Anibal Ibarra was suspended from office last year
They failed to reach agreement on banning Mr Ibarra - who denies any responsibility - from public office for 10 years.
The blaze at the Republica Cromagnon nightclub started when a concert-goer shot a flare into the ceiling.
Many victims died of smoke inhalation as the emergency exits were locked.
The nightclub owner and city officials have also been investigated for their part in the tragedy, one of the worst in Argentine history.
The decision was reached after a long-drawn-out vote broadcast live on national television, and after weeks of bitter accusations and insults.
At least 1,500 people had packed into the nightclub
The city's council ruled that Mr Ibarra must assume some responsibility for the tragedy for failing to ensure public safety inspections were carried out.
The legislative building where the impeachment hearing took place was surrounded by tight security, after a night of protests in which buildings were damaged and people threatened.
The families of the victims placed a huge Argentine flag with photographs of their loved ones on top on the approach to the legislative building.
Their celebrations began immediately the deciding vote was cast.
Mr Ibarra's supporters says he is a victim of a witch-hunt led by his political rivals.