The genus Janibacter is a rare Gram-positive rod-shaped bacterium that mainly exists in the environment. This bacterium can cause bacteremia and may further develop into sepsis, aggravating clinical symptoms. In May 2022, a 9-year-old boy was admitted to our hospital due to "intermittent fever for over one month." Physical examination revealed scattered hemorrhagic rashes over the body, with notable involvement of the postauricular area. Multiple enlarged lymph nodes can be palpated bilaterally in the neck, in the left supraclavicular fossa and bilaterally in the axillae, approximately the size of broad beans, with a firm texture, fair mobility and no tenderness on palpation. Laboratory tests showed a white blood cell count of 2.79×10⁹/L↓, C-reactive protein of 6.41 mg/L↑, and procalcitonin of 0.2 ng/mL↑. Fecal occult blood was positive. Laboratory examinations revealed elevated levels of aspartate aminotransferase (65.6 U/L↑), alanine aminotransferase (60 U/L↑), lactate dehydrogenase (480 IU/L↑), and creatine kinase isoenzyme (30.7 U/L↑). Metagenomic next-generation sequencing (mNGS) identified Janibacter, with 408 sequences detected. The child was definitively diagnosed with Janibacter infection. After treatment with intravenous immunoglobulin, linezolid, and co-trimoxazole, the clinical symptoms improved, laboratory tests normalized, and no pathogens were detected on follow-up mNGS. This child represents the first reported pediatric case of sepsis caused by Janibacter melonis infection, both domestically and internationally.