Rahul Phatangale was killed allegedly during the violence near Koregaon Bhima in Pune district. A case against unidentified persons had been registered.
Phatangale was allegedly assaulted by a group of people when he was on his way home.
"We have arrested three persons from Ahmednagar and all of them have confessed to attacking Phatangale with stones and sticks," said Superintendent of Police Suvez Haque.
Police have withheld the identity of the three accused.
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"Faces of some of the attackers were clearly seen in the footage, and based on the video, these three persons were tracked down," said the officer.
More people were involved in the incident and police were trying to identify them, he said.
The violence occurred during the bicentennial event to commemorate the Koregaon-Bhima battle in which British imperial forces comprising Dalits had defeated the army of Peshwas.
Dalits view the historic battle as the defeat of "casteist" Peshwas who had represented the Maratha empire.
Lakhs of Dalits visit the Koregaon Ranstambh (victory pillar) every year to commemorate the Koregaon Bhima battle.
It is seen as a symbol of Dalit assertion against upper- caste rulers, but some pro-Hindutva organisations had opposed celebration of the British victory against a native army.