Background Hallux valgus deformity is a common sequel of spastic cerebral palsy. Methods Twenty ambulatory patients (24 feet) suffering hallux valgus deformity, with painful forefoot and restricted footwear, secondary to spastic cerebral palsy acquired perinatally, were treated with great toe metatarsophalangeal (MTP) arthrodesis using percutaneous K-wires for fixation. The mean age at the time of surgery was 16.2 years (range 14-18 years). They were retrospectively evaluated for the results after arthrodesis at a mean interval of 3 years and 4 months (range 3-4 years) by physical examination and radiographs. Results All patients had a stable painless aligned great toe, with \10°valgus, \20°dorsiflexion and neutral rotation after arthrodesis, evidenced by improvement in pain, cosmesis, functional activity, footwear, callosities and hygiene, as well as by significant improvement in the measures of the MTP and the intermetatarsal angles (IMA) by postoperative radiographs. Neither non-union (pseudoarthrosis) nor recurrence of the deformity developed. Complications included superficial wound slough in a single case. Using the modified American Orthopaedic Foot Ankle Society (AOFAS) Hallux Metatarsophalangeal-Interphalangeal Scale, 18 feet (75%) were classified as excellent and six feet (25%) as good. Neither fair nor poor cases were recorded. Conclusion Hallux valgus deformity in adolescents with spastic cerebral palsy is best treated by great toe MTP arthrodesis to improve segmental foot malalignment and dynamic foot deviation.