Purpose: Existing literature is limited in its ability to consider start-ups as a knowledge broker to trigger innovation in a supply chain ecosystem (SCE). In a traditional SCE, start-ups are relatively isolated, leading to structural holes that limit knowledge sharing among members. This paper aims to overcome that limitation and to build frameworks that help to illustrate the interaction between knowledge management and sharing, start-up innovation and an ecosystem from a supply chain perspective. Design/methodology/approach: Following a qualitative approach, this study theorizes about the role of start-ups as knowledge brokers and the implications of knowledge management and sharing with members in an SCE concerning innovation. Conceptual analysis is used for examination, and this study uses a set of qualitative tactics to interpret and generate meaning from the existing literature. Findings: This study develops two frameworks to provide insight into how start-ups can trigger innovation as knowledge brokers in an SCE. The first framework shows how start-ups, and their knowledge base, influence supply chain members and the overall ecosystem, highlighting the isolated function of start-ups and the issue of structural holes in a traditional SCE. The authors propose a model that illustrates how structural holes can be bridged within an SCE, thereby demonstrating how start-ups redefine the ecosystem architecture according to their knowledge broker position in the SCE. Originality/value: By expanding insight into the concepts of how start-ups can trigger innovation as knowledge brokers in an SCE, this paper extends the so-far neglected area of start-ups and knowledge brokers. This study clarifies the conceptual and theoretical components and processes in an SCE and links the different roles of start-ups as knowledge brokers to the respective supply chain members to better understand the implications on the entire SCE.