A live feed of a webcam in Amsterdam depicted hundreds gathering in front of a stand at the central square. The Netherlands' GroenLinks (translated as Green Left) party claimed good turnout in the northern city of Groningen on its Twitter account.
"Dear Monsanto, if you don't love life, don't kill humans, don't kill animals, don't kill our planet, kill yourself," read a placard photographed by a participant in Brussels, Belgium.
In Berlin, a live video stream broadcast hundreds of people marching across the streets, beating barrels painted yellow with black biohazard signs and carrying anti-Monsanto banners.
The MAM group, coordinators of the protest actions, claimed on its website that 428 cities in 38 countries were planning to hold peaceful demonstrations on Saturday.
Earlier, at least three French cities out of 12 registered on the group's website, held demonstrations against Monsanto, and protests in Australia, South Africa and Ghana were particularly active.
The MAM movement seeks to shed light on the dangers surrounding Monsanto's genetically modified seeds and herbicides linked to cancer, particularly Roundup.
A Monsanto spokesperson told Sputnik earlier in response to protesters' accusations that people are free to express their opinion, adding that the company is committed to "making a more balanced meal accessible for everyone."
Initially founded as a food additive company in 1901, Monsanto employs 22,000 people across 61 countries and is the world's leading producer of genetically engineered seeds and chemical herbicides.