Tuesday’s motion was advisory, meaning cabinet is not legally obliged to act on it.
Demonstrations were held outside the council’s headquarters in Truro during the full council meeting.
Green group leader councillor Drew Creek said reintroducing glyphosate would be harmful to human health as well as the environment.
Creek said he hoped the council would “work collaboratively” with town and parish councils to “explore other options”.
Labour group leader, councillor Kate Ewert, said smaller councils had been “disrespected and ignored” during the process.
“They’ve given them no time to put in back-up plans, essentially just holding a gun to their head to say ‘you have to opt in’.”
