Upper limb spasticity surgery is an area of increasing interest and advances have been made in assessment and management, however treatment of the thumb remains a challenge. This systematic review evaluated current techniques to treat thumb spasticity. A search of three databases identified 14 articles between 2005 and 2023. Studies were assessed for methodological quality and found to be low-to-moderate in most cases. Data was extracted but synthesis limited by heterogeneity in patient groups, procedures, and outcome reporting. Lengthening of the flexor pollicis longus, release of intrinsic muscles, and augmentation of antagonists, often by re-routing of extensor pollicis longus, were reported most frequently. Thirteen studies (92.9%) demonstrated improved thumb spasticity, position, or function, and complications were uncommon, though deformities recurred in up to 30%. Poor quality evidence precluded definitive conclusions on safety and efficacy. Future investigators should focus on standardising outcome reporting, with an emphasis on functional goals.