Participatory Design (PD) is increasingly applied to tackle public health challenges, demanding new disciplinary collaborations and practices. In these contexts, any proposed intervention must be supported by evidence that demonstrates it is likely to have the desired effect, particularly if it relies on investment of public funds. An evidence base can include evidence and theory from prior research, evidence generated through primary research, and evaluation. PD research generates evidence through collaboration directly with people who may use or receive an intervention, understanding their experiences and aspirations in situated contexts, without using formal abstractions or assuming evidence generated elsewhere will be directly applicable. Drawing on a case study of a collaboration with public health experts to develop an intervention using PD, we argue there is value in using existing evidence and theory to engage, inform and inspire intended users of an intervention to participate in the design process. This article aims to support PD researchers and practitioners to consider how evidence can be integrated and produced through PD, enabling collaboration with other disciplines to produce evidence-based and theory-informed interventions to address complex public health challenges.