[1] Musashi-Seki Station is served by the 47.5 km Seibu Shinjuku Line from Seibu-Shinjuku in Tokyo to Hon-Kawagoe in Saitama Prefecture.

Located between Kami-Shakujii and Higashi-Fushimi, it lies 14.4 km from the Shinjuku terminus.

The station is composed of two side platforms serving two tracks.

[4] In fiscal 2013, the station was the 34th busiest on the Seibu network with an average of 28,803 passengers daily.

[5] The passenger figures for previous years are as shown below.