Background Streptococcus pyogenes (group A β-haemolytic streptococcus, GAS) is a common cause of infections in children; however, invasive forms involving the central nervous system are extremely rare. Meningitis caused by GAS accounts for less than 1% of all cases of bacterial meningitis and is associated with high mortality and a significant risk of neurological complications. Intracranial purulent complications, particularly subdural empyema, are among the least well-documented forms of invasive GAS infection. Case presentation We report a case of an immunocompetent 17-year-old adolescent with acute bacterial meningitis, developed after an upper respiratory tract infection. The course of the disease was complicated by pansinusitis and the formation of bilateral frontal-parietal subdural empyemas with concomitant encephalitic changes. Streptococcus pyogenes was identified as the causative agent in the cerebrospinal fluid. Initial empirical treatment with vancomycin and ceftriaxone led to partial improvement; however, a subsequent deterioration in the patient’s condition necessitated repeat neuroimaging and adjustment of the antimicrobial therapy. Prolonged treatment resulted in a gradual improvement in clinical, laboratory and imaging findings. The patient was treated conservatively without neurosurgical intervention and discharged in a satisfactory condition with regression of neurological symptoms. Conclusions Despite the rarity of subdural empyema caused by S. pyogenes, it should be considered in the differential diagnosis in children and adolescents, especially in the presence of concomitant sinonasal infection. The present case highlights the importance of early diagnosis, timely use of neuroimaging, and dynamic correction of antibiotic therapy. A multidisciplinary approach is key to preventing severe complications and achieving favourable clinical outcomes.