<p>The market uptake of recycled glass fibre (rGF) from conventional recycling routes is limited by fibre discontinuity, reduced mechanical performance, and handling challenges. This study evaluates a closed-loop recycling approach in which rGF reclaimed from composite wind turbine blade waste via pyrolysis is reintegrated into glass fibre (GF) melt formulations to produce virgin-quality GF with recycled content. A life cycle assessment (LCA) was conducted to compare the environmental impacts of GF with recycled content against virgin GF across multiple impact categories. Results show that GF with recycled content can achieve environmental impacts comparable to, or lower than, virgin GF provided the pyrolysis process is energy self-sustaining and limits polymer combustion to 20–25 wt%. Under these conditions, the carbon footprint of GF with recycled content is equivalent to virgin GF, while enabling a closed-loop recycling pathway. The findings define quantitative performance targets for recycling technologies and demonstrate the potential for circular, low-impact GF production.</p>