She was raised in New York City with an affluent family. .Her birth-name was Ruth Sawyer, and she published under this name after she was married.Upon the death of her father, a New York City importer, the family lost most of their wealth and their home in New York City.They were forced to move to their summer cottage in Maine and live off the land, an experience that Sawyer describes in her autobiographical children's novel, The Year of Jubilo.Her New York childhood is described in Roller Skates. The protagonist of these novels is "Lucinda Wyman", which was also the name of Ruth Sawyer's grandmother; but "Lucinda" was not Ruth's actual name.

Sawyer travelled to Cuba in 1900, to teach storytelling to teachers organizingkindergartens for children orphaned during the Spanish-American War.She returned to New York to study folklore and storytelling at Columbia University, where she got a B.S. in 1904.During two summers in 1905 and 1907, sheworked in Ireland for the New York Sun and spent time in the countrysidecollecting Irish folk tales. Using these tales, she wrote Old Con and Patrick in 1946.

Sawyer married Albert C. Durand, an eye doctor. The couple raised two children, Margaret (Peggy) and David, in Ithaca, New York. Peggy, a children's librarian, married Robert McCloskey, who later became a children's book author himself. David, an economist and statistician, was a professor at the MIT Sloan School of Management.

In 1965, she was awarded the Laura Ingalls Wilder Medal for her work.

Her first published work was The Primrose Ring in 1915, of which a movie was made in 1917 (starring Loretta Young). Her best-known book is Roller Skates, which won her the Newbery Medal in 1937.Like Roller Skates, a number of Sawyer's books are autobiographical accounts of her childhood and reveal an interesting perspective on American life at the end of the 19th century. These include The Year of Jubilo (1940) and Daddles, The Story of a Plain Hound-Dog (1964). As well as "Le berceau de Bo le Bossu"( a religious, Christmas folktale in Saint-Malo) Another tale Journey Cake Ho! written in 1953 and illustrated by Robert McCloskey was a Caledcott Honour Book.

Sawyer also wrote non-autobiographical novels for children, such as The Enchanted Schoolhouse (1956; ill. Hugh Troy)and The Year of the Christmas Dragon (1960; ill. Hugh Troy), and a scholarly work, The Way of the Storyteller(1942). She published a number of collections of folktales, such as This Way To Christmas (1916) (which featured an illustration by a young Norman Rockwell) and My Spain: A Storyteller's Year of Collecting (1967).