Objective To explore the efficacy and safety of the ketogenic diet (KD) in the treatment of genetic developmental and epileptic encephalopathy (DEE). Methods Clinical data from 42 children with genetically confirmed refractory epileptic encephalopathy treated in the Department of Neurology, Jinan Children’s Hospital, between January 2021 and October 2023 were retrospectively analyzed. A classic KD protocol was implemented, and outcomes including seizure frequency, electroencephalogram (EEG) improvement, and adverse reactions were observed at 3, 6, and 12 months post-treatment. Results Among the 42 children, the seizure-free rates at 3, 6, and 12 months of KD treatment were 16.7%, 16.7%, and 14.3%, respectively, while the effective seizure control rates were 69.0%, 52.4%, and 35.7%. At 3 months, comparison of baseline characteristics between the effective and ineffective groups showed no statistically significant differences in gender (P=0.095), age at onset (P=0.648), age at KD initiation(P=0.768), disease duration before KD (P=0.519), presence of abnormal brain MRI findings (P=0.226), epilepsy syndrome classification(P=0.344), or ion channel gene involvement (P=0.066). EEG improvement rates at 6 and 12 months were 54.2% (24 cases) and 42.8% (14 cases), respectively. Retention rates for KD at 3, 6, and 12 months were 100.0%, 71.4%, and 42.8%. Adverse reactions occurred in 7 patients (16.7%), primarily gastrointestinal symptoms (vomiting, constipation, diarrhea; 6 cases) and elevated uric acid (1 case), with no severe adverse events reported. Conclusion KD is an effective treatment for genetic DEE with favorable short-term safety, though long-term adherence requires attention.