Background: Esophagus cancer patients are at high risk of malnutrition. This study was performed to assess the nutritional status and dietary intake of newly diagnosed esophageal cancer patients in Vietnam National Cancer Hospital (NCH). Methods: A cross-sectional study was conducted on 206 early esophageal cancer inpatients after gastrostomy from September 2017 to June 2018. The chi-squared test, Fisher exact test, and Mann–Whitney test were performed. The software of the Vietnam National Institute of Nutrition was used to evaluate the dietary intake of patients. Results: All the participants were male with a mean age of 57.1 ± 8.5 years. Overall, 87.4% of patients had dysphagia. Furthermore, 82.5% and 90.8% of patients reported weight loss one and six months pre-diagnosis, respectively. Moreover, 52.9% of patients suffered from mild/moderate malnutrition and 29.6% of patients had severe malnutrition according to the Patient-Generated Subjective Global Assessment (PG-SGA). The body mass index (BMI) and mid upper arm circumference (MUAC) measurement revealed 47.6% and 50% of undernourished patients, respectively. The proportions of patients having malnutrition were 10.7%, 55.8%, and 27.2% according to albumin, prealbumin, and total lymphocyte counts, respectively. The means of energy, protein, lipid, and carbohydrate in the patients’ 24 h preoperative diets were 973.6 ± 443.0 kcal/day, 42.4 ± 21.6 g/day, 31.0 ± 15.5 g/day, and 130.0 ± 64.5 g/day. The total energy, total protein, animal protein, total lipid, and plant lipid in the dietary intake of patients were strongly correlated with age, economic classification, and PG-SGA (each p < 0.05). The total energy intake increased day by day, with the average energy intake of 1343.9 ± 521.3 kcal on the seventh day. Energy and protein response rates increased day by day and were highest at 7 days post-operation at 18.0% and 19.4%. Conclusion: Malnutrition and insufficient intake are noteworthy in esophageal cancer patients. The PG-SGA is strongly correlated with the dietary intake of patients. The results from this study will help medical staff to prevent malnutrition and improve the nutritional status of esophageal cancer inpatients. Furthermore, public awareness should be raised on recognizing weight loss as an early symptom of esophageal cancer and the utilization of preoperative assessment tools for nutritional assessment and malnutrition management.