A sequel written and illustrated by George was published in 1991, more than three decades after the original. Over the next 16 years there were three more sequels, a third novel illustrated by George and two picture books illustrated by Daniel San Souci. All the sequels were published by Dutton Children's Books, an imprint of Penguin Books since its acquisition of the original publisher E. P. Dutton in 1986.
- My Side of the Mountain (1959), illus. George OCLC 276356
- On the Far Side of the Mountain (1990), illus. George OCLC 20631814
- Frightful's Mountain (1999), illus. George OCLC 41445775
- Frightful's Daughter (2002), illus. Daniel San Souci, 32 pages OCLC 50556042
- Frightful's Daughter Meets the Baron Weasel (2007), illus. San Souci, 48 pp. OCLC 76863950
The three novels were issued in an omnibus edition that retains the original pagination, about 600 pages in sum: My Side of the Mountain Trilogy (2000). OCLC 45610215
In 2009, Dutton published A Pocket Guide to the Outdoors: Based on 'My Side of the Mountain', by George and her daughter Twig C. George. According to a library summary: "This guide to the outdoors provides advice and instructions on camping, building shelters, finding water, and cooking outdoors. Some activities may require adult supervision." Inside responsibility credits John C. George and T. Luke George as well. OCLC 311783530