Background: Primary hyperparathyroidism (PHPT) is increasingly detected through routine biochemical screening. Despite this, fatigue remains a prevalent yet under-recognised symptom that may significantly impair quality of life, even in patients traditionally classified as having mild or “asymptomatic” disease. While parathyroidectomy has been shown to improve overall symptom burden, fatigue-specific outcomes remain incompletely defined. This study aimed to quantify short-term changes in fatigue following parathyroidectomy using a validated patient-reported outcome measure. Methods: A retrospective analysis of prospectively collected data was performed in adults with biochemically confirmed PHPT after exclusion of MEN1 and MEN2 syndromes, undergoing parathyroidectomy at a tertiary endocrine surgery unit between August 2024 and August 2025. Fatigue was assessed pre-operatively and at three weeks post-operatively using the Fatigue Assessment Scale (FAS). The primary outcome was change in total FAS score. Results: Of 51 eligible patients, 46 were included in the final analysis. The mean age was 60 years, and 87% of patients were female. Pre-operative fatigue (FAS ≥22) was present in 73% of patients. Mean FAS scores improved from 29.0 ± 9.7 pre-operatively to 19.0 ± 5.0 post-operatively, corresponding to a mean reduction of 10.4 ± 9.5 points (p < 0.001). Biochemical cure was achieved in all patients. Patients reporting fatigue at baseline demonstrated a significantly greater reduction in FAS scores compared with those without baseline fatigue (−13.1 ± 9.4 vs −5.8 ± 7.0; p = 0.03). No significant differences in fatigue improvement were observed according to sex, pathological diagnosis, or severity of hypercalcaemia. Conclusion: Parathyroidectomy was associated with early, statistically and clinically significant improvements in patient-reported fatigue. These findings highlight fatigue as a meaningful and modifiable symptom in PHPT and support consideration of patient-reported outcomes when evaluating surgical benefit.