In recent years, textile recycling has emerged as an important strategy for reducing the environmental impact of supply chains for various products. But the environmental benefits of recycling might not be systematic, and it is useful to know under which conditions using recycled textile fibers is preferable than virgin materials. The objective of this study is to investigate the potential of textile recycling to reduce environmental impact using a probabilistic life cycle assessment (LCA) approach, applied to a case of open-loop recycling to replace virgin thermoplastics by polyester textiles. The variations of some sensitive parameters are used to test their influence on the probability of the recycling scenario outperforming the reference one using virgin materials. The parameters evaluated are the waste collection distance, the product distribution distance, the amount of additives added to the recycled fibers, the replacement rate, and the origin of the substituted reference product. Out of the 18 impact categories assessed, the recycling scenario outperforms the reference one for eight of them and for every instance of calculations. On the contrary, for other categories, the product made from recycled fibers presents greater environmental impacts, even when large background uncertainties are considered. Therefore, multicriteria assessment is highly recommended when assessing the environmental impact of textile recycling. Well-studied parameters such as the replacement rate or the substituted product’s origin affect confident decision-making for seldomly studied, local impact categories such as terrestrial ecotoxicity. While demonstrated here for a specific case of open-loop recycling, these results can be generalized to other cases where used textile substitutes virgin plastic materials.