While literature on sustainability transitions has generally portrayed incumbent firms as reluctant to engage in sustainable niches and primarily employing strategies that aim to limit niche growth, practice offers many examples that contradict this. In this paper, we mobilize insights from organizational literature, and particularly the concept of entry modes and entry timing from the international business and strategy literature, to investigate incumbent firms’ engagement in sustainable niches through the introduction of new products, collaborative efforts with new entrants, the introduction of new brands, mergers & acquisitions, and investments. We focus on entry modes of incumbent firms, including food firms, meat processors, retailers, and food service firms, in meat substitute markets in the United States (US), the Netherlands (NL), and the United Kingdom (UK). We identify distinct entry mode patterns for the four firm types and that the entry modes of different types of incumbent firms vary in their timing and commitment towards the plant-based meat substitute niche. Contrary to the general consensus stemming from previous literature on incumbent engagement in transitions, our case shows that incumbents proactively engaged with niche products incentivized by economic opportunities stemming from changing consumption patterns, which preceded any regulatory action.