Nishi-Ōi Station (西大井駅, Nishi-Ōi-eki) is a railway station on the Yokosuka Line in Shinagawa, Tokyo, Japan, operated by East Japan Railway Company (JR East).

The station is composed of two elevated side platforms and two tracks, and is located below the tracks of the Tōkaidō Shinkansen.

The line coming from Yokohama splits at this station to the Yokosuka Line toward Shinagawa Station and the Shōnan-Shinjuku Line toward Ōsaki Station.

With the privatization of Japanese National Railways (JNR) on April 1, 1987, the station came under the control of JR East.

Shonan-Shinjuku Line services began operating on December 1, 2001.