When asked: "Why would you choose something that looks and tastes like meat but isn't?" - Watson replied: "Because you're not paying for murder."
The star, who recently launched a range of vegan ready meals in Waitrose, said: "You have two options: A) Meat that is made out of dead animals, tastes good but is also linked to a plethora of health issues.
"B) 'Meat' that looks and tastes like the above but is healthier for you and without the dead animals... Which do you choose?"
Watson responded to followers saying they would choose option A, asking: "Which part excites you the most? The dead animal part or the plethora of health issues, genuinely curious."
She also replied to one user who claimed you 'can't beat a big juicy bit of mayt', stating: "You can actually, guessing you haven't even bothered trying."
Watson, who is vegan herself, regularly speaks out about animal-rights. Earlier this year, the Made In Chelsea star slammed an unknown celebrity for wearing fur after previously featuring in an anti-fur campaign.
"Who poses for an anti-fur campaign with PETA and then WEARS FUR? Just shows the intentions with the campaign were never for the animals in the first place," she said.