All educational and commercial institutions in the city remained shut.
Lawyers and civil society persons held candle-light vigils while city residents took out rallies and raised slogans against terrorists and banned outfits.
Ministers and members of provincial assembly also held a prayer meeting at the Civil Secretariat.
Balochistan Chief Minister Sanaullah Zehri had announced an official holiday for all educational institutions.
At least 70 people - most of them lawyers - were killed on August 8 last year when a suicide bomber attacked the civil hospital emergency ward, where lawyers had gathered after the assassination of Bilal Kasi - the president of the Quetta Bar Association.
Quetta has taken the brunt of terrorist and sectarian attacks by separatists and militants in recent years.
Three days after the suicide bombing at Civil hospital, at least 14 people were wounded after the convoy of a judge was targeted in a roadside bombing in the city.
On June 23 this year, at least 14 people including eight policemen were killed in a suicide car bombing in Quetta.