The injection of a local anesthetic in combination with a corticosteroid is an accepted choice in the treatment of plantar fasciitis with recalcitrant heel pain. When the injection is performed properly, post-injection infection is extremely rare. We are reporting a rare case of chronic calcaneal osteomyelitis that developed secondary to a local corticosteroid injection. A 56-year-old lady diagnosed with right plantar fasciitis presented with a 6-month history of pain and a persistent sinus with serous discharge of her right heel following a local infiltration of a corticosteroid. A Magnetic Resonance Imaging demonstrated right calcaneal osteomyelitis with intramuscular abscess. Surgical drainage and debridement were done, followed by antibiotic therapy. A recurrence of infection was not detected throughout the duration of follow-up. It is suggested that a plantar heel injection be done in a more controlled environment, such as in operating theatre, to reduce the risk of infection and to avoid injecting a steroid as compared to platelet-rich plasma (PRP) in view of their safety profiles. However, such an injection should only be offered after conservative treatment has failed, as 80% of patients recover well after initial conservative management.