Post-injection sciatic neuropathy is a recognized iatrogenic complication of intragluteal injection. We report a case of a young adult presenting with progressive complete paralysis of the left lower limb following intragluteal injection. Magnetic resonance imaging (MRI) demonstrated focal thickening and T2/short-tau inversion recovery (STIR) hyperintensity of the sciatic nerve in the gluteal region, without neuroma or discontinuity and without associated muscle denervation changes. These findings were consistent with post-injection sciatic neuropathy, likely representing axonotmesis. MR neurography was useful in confirming the site and extent of injury and in excluding structural complications. This case highlights the characteristic imaging appearance of injection-related sciatic nerve injury and emphasizes the importance of correct injection technique.