Mycobacterial infections are recognised with increasing frequency in cats in the UK. Over 1 per cent of all routine histopathological submissions from UK cats are found to have changes consistent with mycobacteriosis, which is thought to be an underestimate of the true prevalence. Mycobacteriosis can be highly variable in clinical presentation, challenging to definitively diagnose, and difficult to manage to obtain satisfactory clinical outcomes. Additionally, there is potential for zoonotic transmission of infection. Recent research efforts have improved our understanding of the aetiology, pathophysiology and therefore treatment options for these diseases. This article outlines an updated approach to diagnosing and managing clinical cases of feline mycobacteriosis in the UK.