The F Line is one of eight RapidRide lines (routes with some bus rapid transit features) operated by King County Metro in King County, Washington.

The F Line began service on June 7, 2014,[3] running between the Burien Transit Center and "The Landing" in north Renton.

Other major stops and destinations served include Tukwila International Boulevard Link Station, Southcenter Mall, Tukwila Sounder/Amtrak Station, South Renton Park and Ride, Renton Transit Center and the Boeing Renton Factory.

[4] Unlike most of the RapidRide lines, the F Line does not offer scheduled service during late-night and early morning hours.

[4] This corridor was previously served by Metro routes 110 and 140, with the latter carrying 3,500 riders on an average weekday in April 2014 [1] With the implementation of RapidRide, the corridor saw an overall 69 percent increase in service,[1] and ridership has grown 47 percent, with the F Line serving an average of 5,600 riders on weekdays in June 2015.