Background: To date, various forms of physiotherapy are used in the treatment of cubital tunnel syndrome (CuTS). The effectiveness of physiotherapy for CuTS is inconclusive. The aim of this systematic review was to evaluate the effects of physiotherapy in the conservative treatment of CuTS. Methods: The six databases were searched from December 2020 to March 2022. The inclusion criteria were randomised controlled trials, case series, and case reports that evaluate the effects of physiotherapy in the treatment of adult participants with diagnosis CuTS. A total of 11 studies met the eligibility criteria, capturing a total of 187 participants. Results: In three types of papers, pain, muscle strength, and limitation of upper limb function were the most frequently assessed characteristics. Physiotherapy was most often based on manual therapy, neurodynamic techniques, and electrical modalities. One clinical trial rated the risk of bias “high” and the other two “some concerns”. In case-series designs, five studies rated the risk of bias as “serious” and three as “moderate”. Most of the studies showed a significant improvement in the clinical condition, also in the follow-up study. Only one clinical trial showed no therapeutic effect. Conclusion: There is no possibility of recommending the best method of physiotherapy in clinical practice for people with CuTS based on the results of this systematic review. More high-quality studies are required.