After working as a reporter for The New York Times, Perkins joined the publishing house of Charles Scribner's Sons in 1910. At that time, Scribner's was known for publishing older authors such as John Galsworthy, Henry James, and Edith Wharton. However, Perkins wished to publish younger writers. Unlike most editors, he actively sought out promising new artists; he made his first big find in 1919 when he signed F. Scott Fitzgerald. Initially, no one at Scribner's except Perkins had liked The Romantic Egotist, the working title of Fitzgerald's first novel, and it was rejected. Even so, Perkins worked with Fitzgerald to revise the manuscript until it was accepted by the publishing house.
In 1910 Perkins married Louise Saunders, also of Plainfield, who bore him five daughters. Perkins died on June 17, 1947 in Stamford, Connecticut from pneumonia. His home in Windsor, Vermont had been purchased from John Skinner in the 1820s for $5,000 by William M. Evarts, and had been passed down to Evarts' daughter and Max's mother, Elizabeth Hoar Evarts Perkins. She left the home to family members, including her son Maxwell. The home stayed in the family until 2005, and has been restored and reopened as the Snapdragon Inn. The inn houses the Maxwell Perkins Library, which displays and collects items related to Maxwell Perkins and his extended family. His house in New Canaan, Connecticut, the Maxwell E. Perkins House, is on the National Register of Historic Places. His granddaughter, Ruth King Porter, is a Vermont writer, and one of his grandsons is the Riptide TV series actor Perry King.