Background: The surgical treatment of Siewert type II adenocarcinoma of the esophagogastric junction (AEG) is controversial, and no systematic technology has been established. The aim of this retrospective study is to introduce the technology of transthoracic single-port assisted laparoscopic esophagogastrectomy. Methods: Data from patients with Siewert type II AEG who underwent transthoracic single-port assisted laparoscopic esophagogastrectomy in Guangdong Provincial Hospital of Chinese Medicine from May 2017 to December 2020 were analyzed. Results: A total of 35 patients, including 30 males and 5 females, were enrolled in this study. Eight patients underwent proximal gastrectomy while the other 27 patients underwent total gastrectomy. The median operative times were 247.5 (195.0-275.0) min and 290.0 (173.0-530.0) min for proximal and total gastrectomy, respectively. The median lower mediastinal lymph node dissection (LMLD) time was 41.5 (20.0-57.0) min and the median estimated blood loss was 100.0 (20.0-200.0) mL. The median number of harvested mediastinal lymph nodes was 5 [2-13]. Lower mediastinal lymph node metastasis occurred in 9 patients (25.7%). The lower mediastinal lymph node metastasis rate was significantly higher in patients with esophageal involvement exceeding 2 cm [>2 vs. <= 2 cm : 55.6% (5/9) vs. 15.4% (4/26), P=0.03]. The median postoperative hospital stay was 10 [6-73] days. Overall morbidity was 11.8% (4 patients), including 2 cases of pleural effusion, 1 case of pancreatic fistula, and 1 case of anastomotic leakage. Conclusions: Transthoracic single-port assisted laparoscopic esophagogastrectomy is safe and feasible. It has the advantages of reducing the difficulty of LMLD and digestive tract reconstruction.