Splenic abscesses are rare, with a reported prevalence of 0.14–0.7% in autopsy studies. The treatment options for splenic abscesses include intravenous antimicrobial therapy, percutaneous drainage, and splenectomy. Although the dissemination of endoscopic ultrasound (EUS) intervention techniques has made it possible to perform puncture and drainage via the transgastrointestinal route for intra-abdominal abscesses where the percutaneous route has been difficult, there have been few reports of EUS-guided drainage of splenic abscesses. A case of a splenic abscess associated with a perforated duodenal ulcer that was successfully treated with EUS-guided transgastric drainage is described. An 89-year-old Asian woman with a perforated duodenal ulcer underwent surgery at another hospital. After surgery, the patient developed a splenic abscess, for which percutaneous treatment was anatomically difficult. Therefore, she was referred to our hospital for treatment of the splenic abscess using EUS-guided drainage. EUS-guided transgastric drainage was performed under sedation using a convex EUS scope. The splenic abscess, measuring approximately 4 × 3 cm², was punctured using a 19-gauge aspiration needle. A 6-Fr pigtail nasocystic drainage tube was placed in the abscess cavity. The procedure was completed without any complications. After EUS-guided drainage, the abscess cavity decreased in size over time, and the patient had a good clinical course and was subsequently discharged. EUS-guided drainage of splenic abscesses may be a safe and effective therapeutic alternative to percutaneous drainage and surgery; however, large-scale investigations are required to confirm the present findings.