The Rural Municipality of Montmartre No. 126 (2016 population: ) is a rural municipality (RM) in the Canadian province of Saskatchewan within Census Division No. 6 and Division No. 1. It is located in the southeast portion of the province along Highway 48.
The RM of Montmartre No. 126 incorporated as a rural municipality on December 13, 1909.
The following urban municipalities are surrounded by the RM.
The following unincorporated communities are within the RM.
The RM is adjacent to the Assiniboine 76 First Nations Indian reserve.
In the 2021 Census of Population conducted by Statistics Canada, the RM of Montmartre No. 126 had a population of living in of its total private dwellings, a change of from its 2016 population of . With a land area of , it had a population density of in 2021.
In the 2016 Census of Population, the RM of Montmartre No. 126 recorded a population of living in of its total private dwellings, a change from its 2011 population of . With a land area of , it had a population density of in 2016.
The RM of Montmartre No. 126 is governed by an elected municipal council and an appointed administrator that meets on the second Tuesday of every month. The reeve of the RM is Bernard Kotylak while its administrator is Dale Brenner. The RM's office is located in Montmartre.