State Highway 203 is a nearly 39.837-mile (64.111 km) state highway in the U.S. state of Texas. It runs through the Texas panhandle from Hedley to the Oklahoma state line.

SH 203 was added to the state highway system by 1919, as part of SH 13; the former alignment of SH 13 via Wheeler became SH 33 and is now SH 152. By 1926, SH 13 had taken the alignment that became US 66, while the route through Wellington became State Highway 52. By 1936, the part of SH 52 east of Wellington remained, but the highway west of Wellington was renumbered SH 203, along with a proposed route from Wellington to the state line near Dodson. In late 1945, the state renumbered the route via Dodson as part of Farm to Market Road 338 and rerouted SH 203 to absorb the rest of SH 52. There have been no changes to the routing of SH 203 since 1945.

SH 203 heads northeastward from Hedley. It meets the beginning of SH 273 after leaving that town. SH 203 then turns more easterly and passes through Quail. North of Wellington, it overlaps US 83. It then ends at the Oklahoma state line, where it becomes SH 9.