Background/Objectives: Pulmonary metastasectomy is widely performed in sarcoma, yet patient selection remains empirical and no randomised evidence supports it. We aimed to identify clinicopathological factors associated with overall survival (OS) and disease-free survival (DFS) after pulmonary metastasectomy for bone and soft-tissue sarcoma. Methods: Observational single-centre cohort study combining a retrospective phase (June 2014–December 2016) and a prospective phase (January 2017–January 2021), with follow-up closed in January 2022. Survival was estimated using the Kaplan–Meier method and compared by log-rank testing; variables with p < 0.2 entered a multivariable Cox model selected by the Akaike information criterion. Results: Fifty-seven patients (34 men; mean age 52.8 ± 14.0 years) underwent 80 metastasectomies; 46 (80.7%) had soft-tissue and 11 (19.3%) bone sarcoma. Complete (R0) resection was achieved in 73 procedures (91.2%). Morbidity was 13.8%, with no 30-day readmission or mortality. After a median follow-up of 54.0 months, median OS was 34.0 months (1-, 3- and 5-year OS 82.5%, 46.7% and 32.6%) and median DFS 7.0 months. Incomplete resection was the factor most strongly associated with adverse outcome for both OS (HR 6.54, 95% CI 2.49–17.14) and DFS (HR 8.66, 3.26–23.03). Early metastatic appearance was independently associated with worse OS (HR 2.60, 1.20–5.65) and synchronous presentation with earlier recurrence (HR 2.54, 1.24–5.19). Occult nodal involvement, present in 6.5% of assessed procedures, was associated with survival univariably (p = 0.010). Histological subtype, surgical approach, extent of resection and number of nodules resected had no independent effect. Conclusions: Completeness of resection is the factor most strongly associated with outcome. Early metastatic appearance identifies patients in whom surgery alone is unlikely to be sufficient, and nodal staging should accompany metastasectomy to better estimate the prognosis.