Warby joined the firm's innovation and new product development team in 2004 and subsequently became the marketing manager for Foster's. She was then made UK innovations director for the brewing group.
As the brewer's marketing chief, Warby will oversee the marketing of S&N's entire portfolio of brands including Strongbow, San Miguel and John Smith's.
Tim Seager, S&N's acting managing director, said: "Sarah brings a great deal of experience and knowledge to this role and her appointment will strengthen our drive to become a brands-led, consumer-focused business."
Warby replaces Seager, who until recently headed up marketing for the firm. Last month, he was promoted to acting managing director amid takeover rumours surrounding the business, replacing incumbent John Dunsmore, who is focusing on the company's Europe-wide strategy. He is expected to be confirmed as full-time managing director.