Brand value co-creation is an essential theme in Marketing research. The research aims to investigate the degree to which brand relationship quality on social media influences Generation Z’s motivation to co-create by applying the Stimulus-Organism-Response framework. The study was based on many theories of brand relationship quality, consumer engagement, brand satisfaction, brand loyalty, and brand value co-creation. In this study, survey method was utilized to collect 316 insights from Vietnamese League of Legends communities. Gathered data was further embedded into Structural Equation Modelling to analyze causal relationships between variables. The findings show that consumer engagement in online e-sport communities, which is positively impacted by brand relationship quality, has a major influence on brand satisfaction and brand loyalty. Brand satisfaction acts as a mediator between consumer engagement and brand loyalty. Consequently, brand loyalty positively influences brand value co-creation. E-sport organizations can use these findings to actively implement strategies that involve the e-sport communities in co-creating brand value.