Background: The agro-food sector faces several sustainability challenges and is in clear need of transitions to become more sustainable. A transition in food production, consumption and supply chains that demand fewer resources and fewer animal products is required to attain sustainability in the agro-food sector. This transition can be done by consuming more plant-based food and providing an alternate option to animal protein by substituting it with plant protein. Purpose: This study aims to understand the technological innovation system shaping around the value chain of Swedish legumes. To investigate the above aim, this research intends to address the following questions: RQ1: How is the innovation system built up, and how do the functions of the innovation system perform around the value chain of Swedish legumes? RQ2: What are the barriers connected to the innovation system that hinders the development of the value chain of Swedish legumes? Method: The methodology used was a qualitative case study with an abductive approach. The data was collected from 8 semi-structured interviews and a literature review of relevant articles. The empirical findings were then analysed using a framework based on Technology Innovation System (TIS). Implications: This research study describes the structural causes that form functional barriers in the innovation system that hinders the development of a value chain for Swedish legumes. The findings of this study provides an excellent opportunity for government agencies and policymakers to guide plans and actions through policies to provide incentives for farmers and research projects in favour of a sustainable transition towards more plant-based food. Also, our study contributes to an understanding of sustainability transitions in the Swedish agro-food sector by analysing how the TIS functions perform around the value chain of Swedish legumes.