Introduction Pfizer-BioNTech (BNT162b2) is one of the mRNA vaccines currently approved by the World Health Organization (WHO) and the Food and Drug Administration (FDA) against COVID-19. Case presentation: Here, we report a case of an 8-year-old female with Guillain-Barré syndrome following the 2nd dose of Pfizer-BioNTech (BNT162b2) vaccination requiring respiratory support who was managed with intravenous immunoglobulin. Discussion: There have been reports of Guillain-Barré syndrome following the Pfizer-BioNTech vaccination. In our case, as the symptoms of GBS occurred right after the vaccination, there could be an association, and this report can add to the existing literature and raise awareness about the possible adverse effects of the Pfizer-BioNTech vaccination. Conclusion: Although most adverse effects following Pfizer-BioNTech (BNT162b2) vaccination have been reported as non-serious, clinicians must be aware of serious adverse effects that, though rare, can follow the administration of Pfizer-BioNTech vaccination and require prompt recognition and management.