As the adoption of segmentectomy for small‐sized lung cancers expands, the need for more challenging completion lobectomy (CL) may arise to address surgical margin recurrence. Herein, we present a case of successful CL using a 4K three‐dimensional (3D) (4K3D) endoscopy after segmentectomy. A 77‐year‐old male patient with lung cancer in the anterior segment (S3) of the left upper lobe underwent S3 segmentectomy. One year later, the patient experienced a recurrence at the surgical margin. CL was successfully performed under 4K3D endoscopy, same as the initial surgery. CL after segmentectomy requires meticulous preoperative planning and precise surgical maneuvering, and 4K3D endoscopy provides safe and reliable outcomes.