Nearly all long-distance trains between Helsinki and Turku stop at the Karis railway station.

The station is also the northern terminus of Karis-Hanko commuter trains and used to be the westernmost terminus of Helsinki commuter rail (Y line) in 2002–2016, although the station was served by one Y line commuter train service to Helsinki at 5.44 in the morning (HL 8570) and an L line service from Helsinki arriving at 0.39 in the morning (HL 8525) until the municipality stopped purchasing them from HSL in June 2021, resulting in their withdrawal.

The Karis railway station was founded to serve a privately owned track between Hanko and Hyvinkää, and taken into use in 1873.

After a few years, the privately owned track had only made a loss, and the station was transferred over to the Finnish state.

[3] The station became a crossing point in 1899, when the track between Karis and Turku was opened.