An 8‐year‐old, female, spayed, domestic longhair cat presented with progressive pelvic limb weakness, lethargy and weight loss. Physical examination identified bilateral pelvic limb proprioceptive ataxia, tachypnoea and a subcutaneous nodular lesion on the left flank. Investigations documented a diffuse broncho‐interstitial and nodular pulmonary pattern, pyogranulomatous inflammation in the spleen and an intradural‐extramedullary spinal lesion at the level of L3. Mycobacterium microti was confirmed based on demonstration of organisms on histopathology of the subcutaneous nodule using Ziehl–Neelsen stain together with positive polymerase chain reaction and interferon‐gamma release assay results. Therapy with rifampicin, azithromycin and pradofloxacin was administered for 7 months. Serial monitoring, including repeated magnetic resonance imaging, demonstrated resolution of the clinical signs, pulmonary, subcutaneous and spinal lesions.