INTRODUCTION: Cubital Tunnel Syndrome (CuTS) is a common condition of the elbow that is often treated with surgical decompression of the ulnar nerve but evidence for optimal management is unclear. A previous Cochrane review from 2016 identified very limited evidence to guide conservative management, in particular, night splints. The aim of this systematic review was to update the evidence related to the effectiveness of night splints in the treatment of CuTS. METHODS: We conducted an electronic search on January 15th 2025 of the MEDLINE, Embase, Emcare and CINAHL databases from the last 30 years, using a pre-defined protocol. Risk of bias was assessed using the RoB2 and ROBINS-I tools, with certainty assessed using GRADE. RESULTS: We identified only one randomised controlled trial (RCT), with high overall risk of bias, that compared night splints to a control arm of advice only. This under-powered trial with high loss to follow-up found no difference between groups. One additional RCT and three single-arm studies, all at high/serious/critical risk of bias, suggested the majority of patients with mild/moderate CuTS improve with night splinting but it is unclear whether the effect was due to treatment or time. Evidence certainty was very low. DISCUSSION: We identified a paucity of evidence, of low quality, regarding night splinting. The evidence identified by this review is currently insufficient to determine whether night splints should be recommended for the treatment of CuTS and there is a need for a high-quality research trial comparing night splints to a control intervention.