Global environmental challenges such as climate change, have accelerated the interest in sustainability transitions. Governments and industries are seeking to adopt and promote more sustainable production and consumption practices, in line with the targets set out by SDG12. The packaging industry, a major global contributor to material extraction and pollution, has been driven to replace single-use plastics with paper-based alternatives. Despite previous studies demonstrating the advantages of this transition (e.g. reducing fossil-based emissions), concerns have been raised about the potential negative impacts of the extended use of paper-based packaging (e.g. increased strain on forest ecosystems), and how it may affect climate resilience and carbon capture. The present study seeks to provide novel insights into how the transition from plastic to paper in the Portuguese packaging industry, may be framed under the wider global trend of sustainability transitions, with topics including perceptions towards plastic-to-paper transitions; identification of key policy and societal drivers; transition scenarios; and the potential effect on forest ecosystems. Using a case study approach, a set of 17 semi-structured interviews were conducted with stakeholders from the Portuguese packaging sector (e.g. governmental officials, NGOs and industry professionals). All interviews were recorded, transcribed and analysed using a mixed-method software (MAXQDA). Results show that paper is a sustainable alternative to plastic in the packaging sector, but only in certain applications and that, ultimately, strategies to tackle the trade-offs between the benefits and downsides will need to be carefully developed. While paper does prove to have some benefits, such as reduced emissions, energy usage, biodegradability and higher recycling rate, unexpected negative implications arose, namely the use of plastic or chemical lining in paper packaging, which created unforeseen consequences in the packaging system, representing a maladaptive approach within this transition. The study concluded that European environmental policies are seen as both leverage points and obstacles, causing tensions within the Portuguese packaging sector. Additionally, when comparing obstacles to change and future transition scenarios to achieve whole-system transformation, the study concluded that designing interventions that bridge the product and the system levels may unlock the obstacles identified and lead to more effective transitions towards sustainability.