Background: Tensor fascia lata (TFL) slings are widely used in facial nerve reconstruction (FNR) to restore symmetry and tone, but postoperative trismus is a significant morbidity. This study assessed the feasibility of early rehabilitation using Restorabite, a novel force-controlled trismus device. Methods: Twenty-seven patients undergoing FNR with TFL slings commenced 10 weeks of Restorabite therapy a mean 1.3 ± 1.2 weeks postoperatively. Outcomes included maximal incisal opening (MIO) and trismus-related quality of life (Gothenburg Trismus Questionnaire, GTQ). Results: Mean MIO improved by 13.0 mm (95% CI 11.0–15.0; p < 0.001), with 16 patients improving in trismus severity and 8 no longer meeting trismus criteria (> 35 mm). GTQ scores improved by 17.6 (95% CI 15.4–19.7; p = 0.02), particularly in eating and pain. Benefits were sustained at 6 and 12 months. Radiotherapy was associated with poorer outcomes. Conclusions: Early use of Restorabite is safe and effective for trismus rehabilitation following FNR with TFL slings.