Artificial light at night (ALAN) is a growing threat to nearshore kelp ecosystems around the world, and may compound the existing threats of climate change and herbivory. However, few studies have investigated the interactive effects of artificial light pollution and other threats. In southeastern Australia, sea urchins pose a significant threat to kelp forests - an important habitat that underpin diverse and productive assemblages. However it is unclear the effects of climate change and artificial light at night on trophic interactions between urchins and kelps. A nine-week experiment was run to test the interactive effects of ALAN and ocean warming on urchin consumption rates and behaviour over time. We also measured the effects of artificial light at night and ocean warming on the kelps themselves and investigated whether this further impacted urchin herbivory and behaviour. Kelp consumption was significantly higher in urchins from ALAN treatments compared to dark treatments, and in warm treatments compared to ambient treatments overall, with no interactions with kelp treatment or week overall. Understanding how emergent stressors interact with climate change is essential to formulate new conservation strategies and management approaches that mitigate impacts, buffering the marine environment against the forecasted impacts from climate change.