| State: | OK |
| Type: | SH |
| Route: | 109 |
| Map Custom: | yes |
| Map Notes: | SH-109 highlighted in red |
| Maint: | ODOT |
| Length Mi: | 53.9 |
| Established: | 1957 |
| Direction A: | West |
| Direction B: | East |
| Terminus A: | in Boswell |
| Junction: |
|
| Terminus B: | in Fort Towson |
| Previous Type: | SH |
| Previous Route: | 108 |
| Next Type: | SH |
| Next Route: | 110 |
State Highway 109 (abbreviated SH-109 or OK-109) is a 54 mile[1] (87 km) long state highway in southern Oklahoma. It runs through southern Choctaw County, connecting to US-70 at each end. It has no lettered spur routes.
The highway begins heading southbound from US-70 at Boswell. It turns westbound after about 5 miles (8 km). As it approaches the Red River, it turns back northward and then eastward again to run through unincorporated Gay, 24 miles[2] (38.6 km) into the route. Six miles (9.65 km) later, it meets U.S. Highway 271 and has a concurrency with it lasting about 4 miles[2] (6.4 km), splitting off near Ord. Between Frogville and Huskey it turns back north before ending at US-70 near Fort Towson.
SH-109 originally ran from Fort Towson to Raymond Gary State Park. However, on 1957-04-23 it was redesignated to run from Boswell to Fort Towson.[3] It was realigned several times in the 1960s and once in 1982. Since 1982, the route has remained unchanged.