Seibu Toshima Line (西武豊島線, Seibu Toshima-sen) is a commuter railway line in Tokyo, Japan, operated by the private railway operator Seibu Railway.

Most services connect directly to the Seibu Ikebukuro Line as a local service between Nerima Station and Ikebukuro Station.

[1] It runs parallel to the Toei Oedo Line.

)[2] Station numbering was introduced on all Seibu Railway lines during fiscal year 2012.

Seibu Toshima Line station numbers are prefixed with the letters "SI" (designating it as a branch of the Seibu Ikebukuro Line).