Makers of plant-based meat alternatives are cutting prices, as startups compete with food-industry giants for slices of the rapidly growing market.

Impossible Foods Inc. said Tuesday that it had reduced wholesale prices for its products by 15%. Big food companies—including Nestlé SA, Smithfield Foods Inc., Cargill Inc. and food distributor Sysco Corp.—have recently set plans to introduce their own meat-free patties, sometimes at lower prices than those charged by startups, like Impossible, that helped popularize plant-based...