The school students carried posters reading 'We Care' during their walk from the school premises at Ballygunge area to Rabindra Sarovar in the southern part of the city.
Alan Gemmell, Director India, British Council, and Mikhail Gusev, Deputy Consul, Russian Consulate General in Kolkata, also participated in the walk.
Sonali Sarkar, the school's principal, said 'We Care' for plants, animals and the rich biodiversity.
In short, 'We Care' for the planet, she said.
Two street plays were also organised during the walk, she said.
The three-day celebration began on November 2.
The institution, which started with only six children 70 years ago, currently has about 2,300 students.