The co-creation paradigm can improve public services and address contemporary challenges through the collective citizens' communication input. Relatedly, the process can be enabled or constrained by the existing sociotechnical contextual factors within and outside the public organization. In earlier work, we developed a conceptual framework defining co-creation as a complex socio-technically infused process that can catalyze input communication to generate outcome public value. However, the way public value is co-created in practice is unclear, as our framework is purely theoretical and empirical research within public organizations is sparse. This paper suggests a method to validate our framework and applies it in the framework's initial validation. To this end, we conducted a case study in the Municipality of Thessaloniki, using semi-structured, face-to-face interviews with expert officials. The contribution of this paper is two-fold. First, one-fifth of the framework has been validated, as delimited by the scope of the study, proving that the theoretical constructs have real-life counterparts. Second, because the framework had not been tested before, the suggested validation has also served as a method testing exercise. From a practical standpoint, our study shows how citizens’ input communication is causally linked to output public value through the contextually infused co-creation process. These validated links are instrumental in proving the framework's task-oriented role in signposting outcome public value pathways. In this regard, the practical value of our suggested validation method lies in its potential to improve the framework, enhancing its real-world applicability in view of effective co-creation implementation of citizen-led policies.