<p>The current design practice for aluminum hollow columns subjected to combined axial load and moment and fire is to calculate the capacity of these members, assuming a uniform temperature distribution throughout the section. In this study, <i>P</i>–<i>M</i> interaction diagrams for aluminium hollow columns exposed to non-uniform heating were established, incorporating the influence of thermal gradient due to non-uniform temperature distributions. The interaction diagrams were derived based on the resulting thermal and mechanical responses, with particular attention to the additional moments induced by non-uniform heating. A change in the shape of the P?M interaction diagrams was observed, denoting an increase in the tension failure zone, which was not captured under uniform temperature assumptions. To facilitate practical application, equations were proposed to estimate the axial and bending moment capacities of aluminium hollow columns under pure axial and pure bending while considering the presence of thermal gradients. The findings underline the necessity of incorporating thermal gradients in structural fire design and highlight the limitations of current design methods that assume uniform heating.</p>