Johnston's most popular series of children's books are the Little Colonel Series which take Lloyd Sherman, "the Little Colonel" from age 5 to her decision to marry. Marketed by L. C. Page and Company so that children could request a new one each Christmas. The novels also created a publishing opportunity for their allegories which were published as the Johnston Jewel Series. Later editions were printed with pink covers, blue covers, Shirley Temple movie covers, and a modernized 1960s cover. Holiday editions also kept purchasing opportunities available to Little Colonel fans.
In addition, Johnston wrote a number of other novels, including two Georgina books (1916, 1918), and her autobiography, The Land of the Little Colonel. In the latter she states her love for her readers.