Upper gastrointestinal (UGI) symptoms are among the common complaints among patients visiting health facilities. Because of the scarcity of gastrointestinal endoscopy services and gastroenterologists, the pattern of common upper gastrointestinal diseases has not been well studied in the study setting. This study aimed to determine the pattern of upper gastrointestinal diseases among patients undergoing esophagogastroduodenoscopy (EGD). An institution-based cross-sectional study was conducted at three hospitals in Asella town, southeast Ethiopia. A total of 279 study subjects were included in the study. Three-fourths (74%) of the study participants had abnormal endoscopic findings. The clinical indications for endoscopic examination were dyspepsia (32.6%), peptic ulcer disease (PUD) (27.2%), suspicion of gastric cancer (13.3%), and suspicion of esophageal cancer (11.5%). The abnormal endoscopic findings were esophageal cancer (10.4%), gastric cancer (10%), duodenal ulcer (DU) (9.3%), and gastritis (8.6%). The abnormal biopsy findings were esophageal cancer (7.5%), gastric adenocarcinoma (6.4%), and gastritis (3.9%). Dyspepsia, peptic ulcer disease, and suspicion of UGI malignancies were the most common clinical indications for endoscopic examination, while esophageal cancer and gastric cancer were the most common abnormal endoscopic findings. The most common abnormal biopsy results were esophageal squamous cell carcinoma and gastric adenocarcinoma. It is advised to have a high index of suspicion for esophageal cancer and gastric cancer for patients who present with alarming upper gastrointestinal symptoms in the study setting.