The leaders walked from Holy Family Basilica, where they had earlier held prayers, but were not allowed to go past the police barricade.
They did not attend a formal church service but held prayers outside the church, just a few meters from Parliament Square.
Security officers had barricaded Parliament Road with razor wire as part of heightened security measures ahead of the anticipated Gen Z protests in Nairobi.
Kalonzo, who was accompanied by DAP-K leader Eugene Wamalwa and other leaders, did not attempt to breach the razor wire.
The former Vice President was shielded by his security detail, who formed a protective ring around him as he approached the barricaded road.
The leaders then knelt, laid flowers, and said a brief prayer before retreating under the watch of police officers.
A heavy contingent of anti-riot police has been deployed in and around Parliament Square amid fears of a confrontation with protesters gathering in the city.
Earlier, while addressing the media, Kalonzo said the leaders intended to honour the fallen youth by laying flowers at the spot where he claimed dozens were killed.
“Today, we just want to remember these young people. We intend to lay wreaths in their memory,” Kalonzo said.
“Even if we are denied access to Parliament today, this day must be properly commemorated as a national holiday in the future.”
The former Vice President also praised Kenyans for allegedly choosing to stay at home on June 25 in honour of the Gen Z protesters who died last year.
“A lot of Kenyans have chosen to stay at home in sympathy with the June 2024 deaths. It truly feels like a public holiday—there are barricades everywhere,” he said.
