Semi-arid ecosystems are shaped by frequent wildfires, making the management of landscape disturbances a major conservation challenge in this region. Ant–plant nectar interactions, driven by mutualisms, contribute to ecosystem functioning and biodiversity, with interaction networks a poorly understood aspect of ecosystem recovery from disturbance. In this study we characterised ant interactions with nectar resources in the Scotia mallee region of Australia across three post-fire ages: 35 years (long unburnt), 10 years (old-intermediate) and 6 years (young-intermediate). We did this by describing the number and diversity of interactions between ants and nectar resources and quantifying different ecological network indices. Long unburnt sites were characterised by a higher number of distinct ant–plant interaction combinations, as well as a higher network modularity (Q) and species specialization (d′), reflecting increases in the diversity of plant nectar resources with time since fire. In contrast, the connectance (C) was higher in young-intermediate sites due to frequently repeated interactions between generalist ants and nectar resources, primarily honeydew-producing hemipterans. A comparatively higher incidence of ant–nectar interactions was also observed in young-intermediate sites despite lower vegetation cover, likely due to habitat openness and the dominance of opportunistic ants. Our findings suggest that greater plant diversity in long unburnt sites supports more complex ant-interaction networks indicating higher stability and ecological resilience. Overall, the study highlights the importance of understanding ant–plant interaction networks for assessing biodiversity and informing better management decisions.