Objectives: Previous studies indicated that early ambulation following lung resection can prevent postoperative pulmonary complications (PPCs). However, some patients fail to achieve early ambulation owing to factors such as postoperative nausea, vomiting, or pain, particularly on postoperative day 1. This study aimed to address the critical clinical question: Is ambulation for ≥10 m during initial pulmonary rehabilitation necessary after lung resection surgery? Methods: This retrospective observational cohort study included 407 patients who underwent lung resection surgery for lung cancer between January 2021 and December 2022. Twelve patients with a performance status of ≥2 and 21 patients lacking pulmonary rehabilitation prescriptions were excluded. Patients were categorized into the “early ambulation” group, which included individuals ambulating ≥10 m during rehabilitation on the first postoperative day, and the “delayed ambulation” group. The primary outcome was PPC incidence, with secondary outcomes encompassing pleural drain duration, hospital length of stay, and Δ6-minute walk distance (Δ6MWD: postoperative 6MWD minus preoperative 6MWD). Results: The early and delayed ambulation groups comprised 315 and 59 patients, respectively. Significant disparities were noted in the length of hospital stay (7 [6–9] days vs. 8 [6–11] days, P = 0.01), pleural drainage duration (4 [3–5] days vs. 4 [3–6] days, P = 0.02), and Δ6MWD (−70 m vs. −100 m, P = 0.04). However, no significant difference was observed in PPC incidence (20.6% vs. 32.2%, P = 0.06). Conclusions: Ambulation for ≥10 m during initial pulmonary rehabilitation after lung resection surgery may yield short-term benefits as evidenced by improvements in various outcomes. However, it may not significantly affect the PPC incidence.