This paper investigates the fire resistance of concrete slabs reinforced with thermoformable glass fibre reinforced polymer (GFRP) bars produced with acrylic thermoplastic resin. These bars provide a more flexible and potentially more sustainable alternative to the industry-standard GFRP bars, produced with thermoset resins, which cannot be re-shaped after cured and are hardly recyclable. This study is framed within an ongoing wider research project that aims at evaluating the technical viability of using thermoplastic GFRP reinforcement in civil engineering structural applications. The paper presents the results of fire resistance tests performed on six concrete slab strips reinforced with ribbed thermoplastic GFRP bars, featuring (i) continuous bars between supports, and (ii) spliced bars with straight or 90º bent extremities (obtained through thermoforming), directly exposed to fire. The slabs were simultaneously subjected to a sustained fire load, applied in four-point bending, and the ISO 834 standard fire on their bottom surface. The fire resistance and failure modes of the slabs were compared to those of slabs from previous studies, which shared identical dimensions and detailing, but were reinforced with conventional thermoset GFRP bars, produced with vinylester and vinylester-epoxy resins, with sand-coated and ribbed surface finishes. The fire resistance of the slabs with thermoplastic reinforcement was generally lower or, at most, comparable to that obtained with conventional thermoset bars. Slabs with continuous and 90º bent-end thermoplastic bars failed within 51 and 55 min of fire exposure, whereas those with straight-end splices showed, as expected, lower fire resistance, enduring between 27 and 35 min until collapse.