Background: The aim of this study was to evaluate the outcomes following acute repair of the ulnar collateral ligament of the thumb metacarpophalangeal joint (thumb UCL) using a suture anchor technique. Methods: From 2011 to 2019, we retrospectively identified 40 adult patients from a single centre who had undergone an acute thumb UCL repair (≤6 weeks post-injury). The mean age of the study cohort was 37 years (range 16–70) and 68% (n = 27/40) were male. The short-term outcomes included postoperative complications and failure of repair. The long-term outcomes were QuickDASH, the EuroQol 5-Dimension (EQ-5D), Visual Analogue Scale (EQ-VAS), return to sport and work and satisfaction with outcome. Results: The outcomes survey was completed at a mean of 4.3 years (range 1.0–9.2) for 33 patients (83%). Postoperative complications included self-limiting sensory disturbance (7.5%, n = 3/40), superficial infection (requiring oral antibiotics; 5%, n = 2/40) and wound dehiscence (requiring surgical debridement and re-closure; 2.5%, n = 1/40). No failures of repair were reported. The mean QuickDASH was 3.7 (range 0–27.3), EQ-5D 0.821 (range −0.041 to 1) and EQ-VAS 84 (range 60–100). Of the 32 employed patients, all returned to work at a median of 0.5 weeks (range 0–416) and the mean QuickDASH Work Module was 4.1 (range 0–50). Of the 24 patients playing sport prior to injury, 96% (n = 23/24) returned at a median of 16 weeks (range 5–52) and the mean QuickDASH Sport Module was 4.6 (range 0–25). All the patients were satisfied with their outcome (mean satisfaction score 9.8/10 [8–10O]). Conclusions: Thumb UCL repair using a suture anchor technique is safe and effective up to 6 weeks post injury. Pain and stiffness may persist in the longer term, but most patients report excellent upper limb function and health-related quality of life. The majority return to work and sport and are highly satisfied with their outcome. Level of Evidence: Level IV (Therapeutic)