Shiv Sena chief Uddhav Thackeray, who is the grandson of Prabodhankar, was present on the occasion.
Fadnavis termed Prabodhankar as "the great social reformer who fought against all the odds" and hailed his efforts to wipe out social disharmony.
"Prabodhanji fought against all the odds when the society was in the grip of illiteracy, untouchability, superstitions, and created an atmosphere of public opinion against these social evils," said the Chief Minister.
He said installation of (Prabodhankar's) portrait inside the hall of BMC was a "delayed decision and it should have been taken long back".
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He is the father of late Shiv Sena supremo Bal Thackeray.
"The path of social transformation was well followed by his son Bal Thackeray who founded Shiv Sena to protect the Marathi 'manoos' (people) in Mumbai and Bal Thackeray's legacy is being carried forward very well by his son Uddhav Thackeray," added Fadnavis.
Uddhav thanked the Chief Minister, corporators and team of municipal officers who played a key role in installing his grandfather's portrait.
Uddhav also outlined the work of social reforms done by his grandfather like abolishing child marriage, untouchability and women empowerment.
Meanwhile, Mehta launched several initiatives to
facilitate Ease of Doing Business while Ambekar launched Automatic Napkin Vending Machines.
"We have made the entire shop licensing and renewing process online which would not only end the inspector raj, but also help applicants to get the licenses while sitting at home," said Mehta adding the BMC has also simplified the application form.
Before today, the corporation hall had only two portraits - of philanthropist and pioneer of Mumbai's development Nana Shankarseth and Dadasaheb Donde, one of the leaders of the Samyukta Maharashtra movement.