The TMC supremo began the protest march from Red Road in heart of the city, and it is set to culminate at Jorasakho Thakur Bari, the residence of Nobel laureate Rabindranath Tagore in north Kolkata, around 4 km away.
For three consecutive days, Banerjee, who has been at the forefront in opposing the NRC and the citizenship law, will conduct mega rallies crisscrossing the city and neighbouring Howrah in protest against the law.
Governor Jagdeep Dhankhar has dubbed the rallies as "unconstitutional and inflammatory act" and has urged the chief minister to devote time to retrieve the grim situation.
In the districts, agitators have blocked thoroughfares in East Midnapore, Murshidabad, Malda, Nadia and North 24 Parganas, inconveniencing hundreds of commuters, they said.
In Malda district, protestors have assembled outside Shamsi Railway station.
Several express and local trains have been cancelled or delayed due to the ongoing protests.
A spokesperson of the railways said demonstrators have blocked the tracks in Sealdah-Diamond Harbour
and Sealdah- Namkhana sectors.