"I am telling him directly from here, 'Your justice will not crush us, '" he said.
"Nobody should think this march has ended; this march is a beginning", he said to the huge crowd, which included government employees who have been suspended following the coup attempt.
Erdoğan has criticized that approach, and, in a typical tactic, accused the marchers of "acting with terrorist organizations and the forces inciting them against our country".
Kilicdaroglu, whose party led the opposition to a controversial April referendum that handed far-reaching new powers to an already-authoritarian Erdogan, launched the protest after a CHP member of parliament, Enis Berberoglu, was sentenced to 25 years' imprisonment last month for revealing state secrets.
"Kilicdaroglu unfortunately offers anarchy to the society by making a call for uprising that targets our order and democracy, and disregards elections", Unal said in a news conference at the party headquarters.
Nearly one year after a faction of Turkey's military tried to assume control of the country, the rally was seen as an attempt by the opposition to wrest back the narrative from Erdogan - who critics say used the coup as an opportunity to crush opponents and solidify his power. "This is just he beginning", he told the vast crowd, thought to be the biggest centre-left rally since 1977, when former prime minister Bulent Ecevit was elected.
"One year on from the coup bid, President Erdogan is stronger than ever", said Ozgur Unluhisarcikli, Ankara office director of the German Marshall Fund of the United States.
A 280-mile, 25-day march against the policies of Turkey's government ended with a massive rally in Istanbul on Sunday.
A decision by USA prosecutors last month to charge a dozen Turkish security and police officers after an attack on protesters during Erdogan's visit to Washington also angered Ankara. He also said he hoped that the U.S. and Turkey could replicate an agreement reached last week between the U.S., Russian Federation and Jordan for a ceasefire in southwestern Syria in the north of the country.
"Justice is a right, we want our right back", he said.
"We marched because the judiciary is under a political monopoly", he added. Two people have suffered cardiac arrests, one of whom has died.
Turkey subsequently embarked on the most extensive crackdown in its modern history, arresting over 50 000 people and sacking 100 000 more from their jobs.
Earlier on Sunday, Istanbul Governor Vasip Sahin said 15,000 police officers were deployed to safeguard the CHP rally in the city's Maltepe district, which is home to the prison where Berberoglu is being held.