On Sunday, Kilicdaroglu addressed a rally in Istanbul's Maltepe district, which came on the final day of a 450 kilometers (280 miles) march from Ankara to Istanbul, protesting a judicial decision against one of his fellow party lawmakers.
USA officials have been critical of the methods Erdogan has used to consolidate power since a failed coup attempt in 2016, which include arrests of purported political dissidents and journalists.
Despite their differences, however, the government and opposition leaders appeared to be taking great pains to prevent a major confrontation as the march reached its culmination. Large numbers of police officers escorted the marchers but did not interfere.
For the last half mile or so of the march Sunday, Kilicdaroglu walked alone with a banner bearing the word "justice".
Addressing the throng, CHP leader Kemal Kilicdaroglu said his 25-day march is the first stage of a long campaign. "It is important to recognize the exceptionally peaceful nature of this process, as well as its very specific goal".
The demonstration was meant to be balanced, and reportedly did not contain party flags or slogans as they were banned by organisers. As the night unfolded, President Recep Tayyip Erdogan called on his civilian supporters to take to the streets of Istanbul.
Detention warrants have been issued for 30 more people, according to the agency.
Mr Erdogan claims to be cracking down against those who support militant organisations, but the government definition of what constitutes backing terrorism is so broad it has led to the arrest of thousands of civil servants, journalists, campaigners and other workers. Kilicdaroglu commended his supporters for completing the march peacefully and thanked the security forces for their management of the crowds.
A populist leader who has dominated Turkish politics for about 15 years, President Erdogan is a deeply polarizing figure, equally loved and hated by rival political camps within Turkey.
But the protest is also a sign that Turkey remains staunchly divided.
Sunday's Justice March has drawn some support from other factions and parties.
More than 240 people were killed in the coup attempt.
"We're making some progress down in Syria, we're hopeful that we can replicate that with Turkey on some areas in the north part of Syria", he said.
Turkey has not ruled out a new cross-border operation in Syria against the YPG, which could spark a risky escalation with the US.
"The ones who think they are tricking Turkey by saying they are going to get back the weapons that are being given to this terrorist organization will realize that they are making a mistake eventually", he told members of his ruling AK Party.