Seoul Transportation Corporation, branded as Seoul Metro (Korean: 서울교통공사), is a municipal-owned corporation owned by Seoul Metropolitan Government, and one of the two major operators of Seoul Metropolitan Subway with Korail.

On May 31, 2017, Seoul Transportation Corporation was formed after a merger of Seoul Metro Corporation and Seoul Metropolitan Rapid Transit Corporation to more efficiently operate services on lines 1–9.

In South Korea, seniors aged 65 and over can ride the subway for free. However, due to this initiative, the Seoul Metro's deficit is getting worse.

A declining birthrate and aging population are expected to further worsen public finances, and there is even talk of raising the age limit for free passes.

Seoul Metro, the operator of the subway system in Seoul, has suffered a net loss of around 1 trillion won annually since 2020, with an accumulated net loss of 14 trillion won. A similar problem is occurring at the Korea Railroad Corporation.

Seoul Metro's service covers part of lines 1, 3, 4 and all of lines 2, 5, 6, 7, 8 & 9. Trains from Lines 1, 3 and 4 through operate with Korail services. Seoul Metro controls the railways and stations owned by the Seoul Metropolitan Government.