Plant metabolomic analyses have been mostly applied to analyse metabolomes of crops and model species. However, metabolomic analyses may also be extremely valuable for plant ecologists. Because of the untargeted nature of most metabolomic platforms, the analyses will provide a comprehensive overview of both the primary and secondary plant metabolome. This is especially valuable for chemical ecologists studying plant–herbivore interactions, as both primary and secondary metabolites together determine the performance and preference of herbivores feeding on a plant. A few examples from the recent scientific literature exemplify how metabolomics may yield novel knowledge on the effects of hybridization on plant chemistry, insect resistance and genotype × environment interactions that could not have been so easily obtained with targeted studies alone. Theories and hypotheses regarding optimal defence strategies in plants and invasive plant biology may also benefit from metabolomic analysis. Testable hypotheses built on our current knowledge of plant responses to herbivores and competition may be substantiated and expanded based on metabolomic analyses. Despite some of the limitations that metabolomics analyses may have, the implementation of broad-spectrum chemical analysis in plant ecology will definitively open up new horizons for plant ecologists and enhance our understanding of the importance of plant chemistry in plant–environment interactions for fundamental and applied research.