The short highway travels northwest (parallel to Interstate 45) from FM 646 (future SH 99) in League City, crossing over Clear Creek at the Galveston– Harris county line, to NASA Road 1 west of the Johnson Space Center.

The highway continues into a mix of residential and commercial areas with some fields and trees.

FM 270 heads through residential areas before passing commercial establishments and ending at an interchange with NASA Road 1.

On August 24, 1955, the road was extended east and north to Pickton, creating a concurrency with SH 11.

[7] The designation reverted to FM 270 with the elimination of the Urban Road system on November 15, 2018.