United Nations Secretary General António Guterres wrote on his official Twitter handle @antonioguterres: "Children around the world are showing us their strength and leadership advocating for a more sustainable planet for all."
The day commemorates 30 years of the Convention on the Rights of the Child.
Another post read: "Every child deserves a long and healthy life and that includes a right to be safe, play, clean air, vaccines, education, and health".
UNESCO reminded about the work that still needs to be done on this front: "Worldwide, over 262 million children are #OutOfSchool.
"This year marks the 30th anniversary of the Convention on the Rights of the Child but the #RightToEducation is still not a reality for all."
UNICEF too tweeted: "We believe in a world in which every child is safe, healthy and supported, with a chance to learn and choose the future they deserve."
Rajasthan Chief Minister Ashok Gehlot wrote on his Twitter handle @ashokgehlot51: "Greetings to all little ones on #WorldChildrensDay. On this day, we need to renew our commitment towards protecting child rights and to ensure each child gets to enjoy a full childhood. Every child should get proper care and a healthy environment for development."
Tendulkar posted a couple of pictures on his Twitter handle @sachin_rt and wrote: "I had a wonderful time playing cricket with young boys & girls during my recent visit to Nepal.
"Playing sports teaches a lot about life & shapes our personalities positively. This World Children's Day, let's celebrate every child's right to play, as it has the power to change lives".
( With inputs from IANS )