Thicket Tinamou is the northernmost species of tinamou, and occurs from northern Mexico south to Costa Rica. There is an isolated population (occidentalis) on the Pacific slope of Mexico, from Sinaloa south to Guerrero. Thicket Tinamou occurs north to central Tamualipas in northeastern Mexico; it occurs south along the Atlantic slope to southeastern Mexico, the Yucatan Peninsula, northern Guatemala, and northern Belize. In southern Mexico the distribution crosses to the Pacific slope, and it occurs south along the Pacific slope to western Costa Rica.
The elevational range of Thicket Tinamou is from the lowlands up to 1800 m in Mexico (Howell and Webb 1995), and to 1000 m in Costa Rica (Stiles and Skutch 1989).