The Dutch horticulture sector (Dhc sector) is a significant contributor to the country's GDP and a global leader in horticultural production and trade. However, despite government efforts, the sector faces challenges in achieving sustainable targets. Sustainable startups, the suppliers of innovative solutions, also encounter barriers hindering the implementation of their sustainable business models. This study aims to identify these barriers and propose niche strategies to help sustainable startups effectively implement their business models in the Dutch horticulture sector. To address the research question, the study develops the Sustainable Transition Navigator (STN) model, which integrates the Sustainable Business Model Canvas (SBMC), Technological Innovation Systems (TIS) framework, and niche strategies. The model assists startups in visualizing and optimizing the impact of their niche strategies on their sustainable business models. The STN model is validated and applied to two sustainable startups in the Dhc sector. Through stakeholder analysis and qualitative interviews, the study identifies six clusters of innovation barriers specific to the sector. These findings are incorporated into the STN model to highlight the barriers that sustainable startups must overcome. The practical implementation of the STN model reveals its benefits. Startups find the model valuable for assessing technological viability and selecting appropriate niche strategies. The visual representation of the model facilitates communication within startup teams, emphasizing the importance of regularly revisiting and adjusting strategies. The STN model serves as an online tool for iterative evaluation and adjustment. The flexibility of the STN model allows startups to adapt it to various stages of their journey. By accurately assessing hindering building blocks and influential factors within the TIS framework, startups can identify areas for improvement and formulate relevant niche strategies. Multiple niche strategies can be organized into a timeline, creating an implementation plan that can be continually revisited. This study contributes to scientific and managerial fields by expanding the applicability of the TIS framework, introducing the STN model, and providing practical insights for startups and business leaders. The findings offer guidance for navigating barriers and driving sustainable transitions in the Dutch horticulture sector and other industries.