Plants employ systemic induced resistance as part of their defense arsenal against pathogens. In recent years, the application of mild heating has been found to induce resistance against several pathogens. In the present study, we investigated the effect of root zone warming (RZW) in promoting tomato resistance against the necrotrophic fungus Botrytis cinerea (Bc), the hemibiotrophic bacterium Xanthomonas campestris pv. vesicatoria (Xcv) and the biotrophic fungus Oidium neolycopersici (On). We demonstrate that RZW enhanced tomato resistance to Bc, On and Xcv, through a process that is dependent on salicylic acid. RZW induced tomato immunity, resulting in increased defense gene expression, reactive oxygen species (ROS), and ethylene output when plants were challenged, even in the absence of pathogens. Overall, the results provide novel insights into the underlying mechanisms of warming induced immune responses against phytopathogens with different lifestyles in tomato.