This dataset contains anonymized responses from the online stakeholder survey “Views on sustainable value chains using feedstock from marginal lands,” conducted in 2024 as part of the Horizon Europe project MarginUp! (Grant Agreement 101082089). The survey was distributed across seven case study regions—Hungary, Germany, Spain, Sweden, Greece, South Africa, and Argentina—and targeted stakeholders involved in various stages of biomass-based value chains (e.g., farming, processing, product development). The dataset includes responses to multiple-choice, rating-scale, and open-ended questions. Topics cover stakeholder perspectives on marginal land use for biomass production, sustainability priorities (economic, social, environmental, institutional), perceived challenges, and expectations toward bio-based products. This dataset is intended to foster transparency and enable further research on stakeholder-driven sustainability assessment in bioeconomy transitions on marginal lands.