Seongdong District (Korean: 성동구; RR: Seongdong-gu) is one of the 25 districts which make up the city of Seoul, South Korea.

It is situated on the north bank of the Han River.

[3] The district is home to Hanyang University, one of the most prestigious universities in South Korea.

Seongdong District consists of 20 administrative dongs (haengjeong-dong, 행정동) When Seoul was expanding outward on its size, many parts of Gyeonggi Province were merged to Seongdong District.

Hanyang University, a prestigious university in South Korea, is located in Haengdang-dong and Sageun-dong.