This case series aimed to assess the treatment outcomes of onabotulinum toxin A (BTX-A) in patients with refractory posttraumatic trigeminal neuropathic pain (PTNP) and to conduct a narrative review of the evidence for BTX-A in PTNP. Thirteen patients were treated with BTX-A infiltrations. Patient demographic and pain characteristics, BTX-A administration, and treatment outcomes were retrospectively analyzed. Papers retrieved after a literature search of articles on PTNP treatment using BTX-A were reviewed. Six patients reported an improvement in pain 3 months after the initial BTX-A injection, with 4 patients reporting a 50% reduction. Two patients achieved an 80% reduction in pain score over 3 years of BTX-A therapy. Three patients reported temporary ipsilateral facial muscle weakness. The literature review revealed five case reports on the use of BTX-A in PTNP patients that reported similar effectiveness to the present cohort study. BTX-A may be a potential treatment modality for refractory PTNP, thus reducing the need for polypharmacy. Multiple intraoral BTX-A injections administered over the painful sites are well tolerated, safe and easily practiced. High-quality studies are required to evaluate the long-term therapeutic efficacy and side effects of BTX-A therapy.