The blast punctured the ceiling of the two-storey club and threw bar stools into the streets of Zamboanga City late yesterday evening, police spokesman Alexander Mabalot said.
The club's cashier was killed. Six female bar staff and three male patrons were wounded and brought to hospital for treatment, Mabalot told AFP.
Investigators sifted through debris today searching for bomb fragments. It was not immediately clear if extremist groups were behind the explosion, he said.
"Our city is under constant threat from terrorist and criminal groups," Mabalot said.
In January, one person was killed while 48 others were injured after a parked car exploded in the city's commercial centre, an attack authorities blamed on the Abu Sayyaf group.
The southern Philippines has long been wracked by violence carried out by Muslim separatist guerrillas, Al-Qaeda-linked extremists and extortion gangs.