The Yokosuka Line (横須賀線, Yokosuka-sen^?) is a railway line in Japan operated by the East Japan Railway Company (JR East).

The Yokosuka Line connects Tokyo in Chūō, Tokyo and Kurihama in Yokosuka, Kanagawa. Officially, the name Yokosuka Line is assigned to the 23.9 km segment between Ōfuna and Kurihama stations, but the entire route is commonly referred to as the Yokosuka Line by JR East for passenger service.

The Yokosuka Line runs underground between Tokyo and Shinagawa (parallel to the Tōkaidō Main Line, the Yamanote Line and the Keihin-Tōhoku Line) then branches to the west along the Tōkaidō Shinkansen into the city of Kawasaki. (This alignment, technically known as the Hinkaku Line (品鶴線, Hinkaku-sen^?), was originally built for freight usage; see below.) It rejoins the Tōkaidō Main Line corridor near Tsurumi Station and follows the Tōkaidō Main Line to Ōfuna, where it branches off to the southeast along the original Yokosuka Line toward the Miura Peninsula.

Yokosuka Line local trains make all stops. Most trains have 11 cars, with two of those being Green cars. Other trains between Tokyo and Zushi are made up of 15 cars -- an 11-car set joined to a 4-car set. (Due to shorter platform length at stations south of Zushi, only 11-car trains are operated to Kurihama.)　The Airport Narita rapid service operates as a local train within the Yokosuka Line.