Mycobacteria mucogenicum (M. mucogenicum) is a rarely isolated pathogen. It has emerged as a significant pathogen in immunocompromised patients including those with cancer, organ transplant, or patients on immunosuppressive medication. Chemotherapy may reduce the ability of the bone marrow of these to respond to infection, and patients will be at risk for neutropenic sepsis, which leads to fatal complications. Here, we report a case of an 18-year-old boy was seen at Hospital Raja Perempuan Zainab II, Kelantan with acute lymphoblastic leukaemia (ALL) who presented with catheter-related bloodstream infection (CRBSI) caused by M. mucogenicum. He succumbed due to neutropenic sepsis with multiorgan failure.