Purpose: To report a rare case of non-tuberculous mycobacterial (NTM) choroiditis masquerading as choroidal tumour, where the initial diagnosis was masked by keratitis. Case description: A 57-year-old heroin chaser with a pre-existing left eye blindness due to past blunt trauma presented with diffuse bacterial keratitis on the same side. Systemic examination revealed multiple non-tender cervical lymphadenopathies. B-scan ultrasonography showed a hyperechoic choroidal mass with surrounding exudative retinal detachment, resembling a choroidal tumour. However, computed tomography (CT) and magnetic resonance imaging (MRI) scan findings were suggestive of inflammatory choroidal changes. Inflammatory markers were significantly raised and infective screening was positive for HIV and Hepatitis C. Tuberculosis workup was normal. In view of intractable pain, evisceration was done and his vitreous humour was sent for polymerase chain reaction (PCR). It was reported to be positive for Mycobacterium Fortuitum. Conclusion: NTM ocular infections are rare, challenging to diagnose, and potentially sight threatening. Early recognition and prompt treatment is life and vision saving.