Mr Millea said: "The Hillsborough and Heysel tragedies are events that deeply affected and shaped the consciousness of this city and its people.
At midday, bells in the city's municipal buildings pealed 39 times in memory of the 39 Italian soccer fans who died when a terrace wall collapsed during a European cup final between Liverpool and Juventus in Brussels.
The anniversary of the event has never been formally marked before but last month, a plaque was unveiled next to a memorial for the 96 Liverpool fans who died in the Hillsborough tragedy.
The Heysel commemoration was proposed by the chairman of the council's Hillsborough disaster working party, Peter Millea, at its meeting in March.
Mr Millea said: "The Hillsborough and Heysel tragedies are events that deeply affected and shaped the consciousness of this city and its people.
"It is only right and proper that we remember those who died at both disasters.
Trouble erupted between Juventus and Liverpool fans on Heysel stadium's Y and Z sections about an hour before the European Cup final on May 29 1985.
During the fighting, a group of Italian supporters ran towards a terrace wall which collapsed, crushing 39 fans to death.
Juventus eventually won the match 1-0. The disaster led to all English clubs being banned from European football for five years, with a 10-year ban on Liverpool's participation.
Fourteen Liverpool fans were given three-year sentences - half the terms were suspended - after being found guilty of involuntary manslaughter at a five-month trial in Belgium in 1989.