Forest thinning has been proposed to reduce fire severity. However, evidence to support this strategy in Australia is scant. We completed a detailed empirical analysis of stand history data from forests burned in wildfires in 2009 in south‐eastern Australia, to address the question: Does forest thinning reduce fire severity? The answer varied depending on fire type (Crown Burn vs. Crown Burn/Crown Scorch), forest type, and stand age. For the statistical relationship for Crown Burn, there were no thinning effects in ash‐type forests. For mixed species forests, thinning reduced the probability of Crown Burn in young stands but increased it in older stands. Data for the fire severity category of Crown Burn/Crown Scorch revealed that thinning generally elevated fire severity, irrespective of stand age, forest type, or fire zone. Except for 20‐ to 40‐year‐old mixed species forest subject to Crown Burn, proposals for thinning to reduce fire severity have limited support.