Kicking off the global day of action, demonstrators in Sydney held banners with anti-genetically modified food slogans and told RT's Ruptly video agency they wanted to promote clean food.
"This company has repeatedly committed crimes against the Earth," one of the Sydney event's organizers told the agency.
The worldwide protests' coordinator, the March Against Monsanto (MAM) group, claimed on its website that 428 cities in 38 countries will hold peaceful demonstrations on Saturday.
The MAM movement seeks to shed light on the dangers surrounding Monsanto's genetically modified seeds and herbicides linked to cancer, particularly Roundup.
The $20-billion company employs 22,000 people across 61 countries and is the world's leading producer of genetically engineered seeds and chemical herbicides.