Around 10,000 people converged on the city’s Istiklal Street, some carrying placards reading "The state is a killer" and "We know the murderers," of more than 90 people killed in Ankaray.
Similar demonstrations were held in other Turkish cities such as Izmir, Batman and Diyarbakir, some of which were dispersed with police intervention.
Following the deadly blasts, Russian President Vladimir Putin called for joint efforts on battling terrorism.
"It is necessary to unite efforts in the fight against this evil. What happened in Turkey… it certainly is an impudent terrorist attack, a terrorist crime with scores of victims. And of course it is an attempt to destabilize the situation in Turkey, a neighboring and friendly country for us," said Putin on a televised broadcast.
Earlier in the day, twin explosions targeted activists who gathered outside Ankara's main train station for a peace rally organized by leftist and pro-Kurdish opposition groups. According to a statement released by Turkish Prime Minister Ahmet Davutoglu's office, at least 95 people were killed and 245 wounded in the attacks, 48 of whom are in critical condition.
The leader of Turkey's main pro-Kurdish party labeled the attack as “vicious, barbaric” adding "We are faced with a murderous state which has turned into a mafia and a state mentality which acts like a serial killer."
"Is it possible that a state with such a strong intelligence network did not have prior information on the attack?" asked Peoples' Democratic Party (HDP) leader Selahattin Demirtas.
He added that the blast was similar to the bombing of an HDP rally in Diyarbakir which killed four people ahead of June 7 elections and the attack, blamed on Daesh, in Suruc which left 32 pro-Kurdish activists dead and hundred others wounded.