Ethylene is a gaseous plant hormone that regulates various aspects of growth and development. It promotes shoot growth in etiolated rice seedlings, which is crucial for seedling establishment and has significant agricultural implications. Of the five ethylene receptors in rice, OsERS1 is the most abundantly expressed in seedlings. Therefore, we investigated the localization and role of OsERS1 in shoot growth. When expressed in rice protoplasts, OsERS1 was localized in the endoplasmic reticulum. Knockout mutants of OsERS1 exhibited enhanced shoot growth in etiolated seedlings under normal and ethylene-treated conditions. Shoot growth was also enhanced in the OsERS1 mutants under light conditions. Additionally, the induction of ethylene-responsive genes was increased in the mutants, indicating an elevated ethylene response due to OsERS1 knockout. The mutants also showed increased salt tolerance. In conclusion, our findings suggest that OsERS1 negatively regulates shoot growth and salt tolerance in etiolated rice seedlings.