Background: Pes planovalgus is one of the most common pediatric foot deformities; one can manage it most conservatively. Surgery is only indicated for symptomatic flexible flatfoot with failed conservative treatment. In children, lateral column lengthening surgery is advantageous as it preserves the growth and development of the foot without fusing the joints. Research question: Is lateral column lengthening effective in managing pediatric and adolescent symptomatic idiopathic flexible flatfeet? Materials and methods: Four electronic databases [PubMed, Cumulative Index to Nursing and Allied Health Literature (CINAHL), Embase, and Google Scholar] were searched for relevant articles reporting the outcomes of lateral column lengthening surgery in idiopathic flexible flatfeet of children with a minimum 1-year follow-up. Pre and postoperative radiological outcomes were recorded using talometatarsal angles, talonavicular coverage, calcaneal pitch, and talocalcaneal angle. The functional results were recorded as pre and postoperative American Orthopaedic Foot and Ankle Society (AOFAS) scores. Rehabilitation protocol and complications were noted. Results: A total of 16 studies were included for the final review, with a total of 336 patients (468 feet) with a mean age of 11.65 years. An autologous tricortical iliac crest was the most commonly used graft during lateral column lengthening. There was a statistically significant improvement in the postoperative radiological parameters like anteroposterior (AP) talocalcaneal angle, AP talometatarsal angle, AP talonavicular angle, and in lateral views talocalcaneal angle, talometatarsal angle, and calcaneal pitch in comparison to preoperative values (p < 0.00001). The mean postoperative AOFAS scores had a standard mean difference of −5.24 [95% confidence interval (CI); −6.39, −4.09] from the mean preoperative AOFAS scores, and this difference is statistically significant (p < 0.00001). Complications like pain in the foot, infection, under-correction, graft displacement, and calcaneocuboid or talonavicular joint subluxation were noted. Conclusion: Lateral column lengthening surgery is promising with good midterm clinical and radiological outcomes with acceptable complications for treating symptomatic flexible flatfeet in pediatric and adolescent populations.