The eatery launched a trial of the P.L.T sandwich (plant, lettuce, and tomato) in Southwestern Ontario outlets in Canada on September 30.
Analysis of the trial, conducted by Swiss investment banking company UBS and reported by Reuters, found McDonald's was selling 20-30 plant-based burgers a day, with sales reaching 100 burgers daily in more 'densely populated areas'.
UBS announced its numbers suggest the chain could eventually sell more than 250 million P.L.Ts annually if the sandwich became available in nearly 14,000 US locations - adding up to $325 million in sales for Beyond Meat.
"We believe Beyond Meat has a first-mover advantage - for now - but it appears a door remains open for McDonald's to refine its P.L.T. offering before introducing a plant-based patty in the United States," Analyst Steven Strycula said, according to Reuters.
"Further, we do not know whether MCD plans to single-source or multi-source a U.S. menu item."
Analysts have also questioned whether the demand for plant-based meat is 'sustainable' and 'commercially viable'.
McDonald's hasn't commented on whether its partnership with Beyond Meat will hit the States.