Relapsing polychondritis (RP) is a rare autoimmune disease that may involve the central nervous system. We herein present the first reported case of hypertrophic pachymeningitis (HP) in an RP patient with a concurrent Klebsiella pneumoniae infection. A 48-year-old man developed transient left-sided weakness and numbness, and brain MRI showed diffuse pachymeningitis. Cultures from a dural biopsy identified K. pneumoniae, and RP was diagnosed using an auricular cartilage biopsy. Treatment with corticosteroids and infliximab resulted in symptom resolution. This case highlights the importance of considering bacterial infections in HP associated with RP, while also providing insight into its pathophysiology.