The company intends to retain the business and build it up in its present form.
Chief executive Nick Hughes said: "We have a great team and are delighted to be partnering a company that shares our vision and passion for the business."
Simon Pooler, a director of Montagu, who will join the board of Marlow Foods as a non-executive director, said: "Quorn is a major healthy eating brand in the UK and the team is replicating this success in international markets. Marlow Foods has significant growth potential."
Based in Stokesley, north Yorkshire, with an annual turnover of £80m, the company also makes products ranging from ready meals to sausages and mince.