[2] The two-lane route travels to the northeast, entering Montague County, and crosses the dam along the south shore of Lake Amon G. Carter.

East of the lake, the roadway turns to the north and travels through unincorporated Montague County before entering Bowie.

FM 1125 has a junction with the US 287 freeway and continues into central Bowie as Rock Hill Road.

The designation was extended 1.2 miles (1.9 km) eastward on December 17, 1952, and then to SH 59 south of Newport on October 24, 1953.

The road was extended to the Montague County line on June 28, 1963; the continuation to US 81 in Bowie was established on July 25, 1963, replacing FM 2094.