The first five-station extension will run east from Kungsträdgården with new stations at Sofia, Hammarby Canal, Sickla, Saltsjö-Järla and Nacka.

The second extension would branch off the Nacka extension south of Sofia to Sockenplan via an interchange with the Green Line at Gullmarsplan. This will serve an area where significant new residential and commercial development is planned.

Both extensions are part of an agreement signed in 2013 by the City of Stockholm, Stockholm County Council, the municipalities of Järfälla and Nacka, and Solna Town Council to build 19km of new metro lines by 2025.