Seah was fielded as a People's Action Party (PAP) candidate for Marine Parade GRC in the 2006 general election, and was elected as Member of Parliament for Marine Parade GRC (Braddell Heights ward) in a walkover for the 11th Parliament. Seah was re-elected in Marine Parade Group GRC in the 2011 and 2015 general elections when the PAP team was challenged by the National Solidarity Party and Workers' Party respectively.
