Mateiros is the easternmost city in the state of Tocantins.

It is the only city in Tocantins to border the state of Piauí.

[3] The municipality contains part of the 707,079 hectares (1,747,230 acres) Serra Geral do Tocantins Ecological Station, a strictly protected conservation unit created in 2001 to preserve an area of cerrado.

[4] It contains part of the 724,324 hectares (1,789,840 acres) Nascentes do Rio Parnaíba National Park, created in 2002.

[5] It also contains the 158,885 hectares (392,610 acres) Jalapão State Park, a fully protected conservation unit created in 2001.