The Rural Municipality of Martin No. 122 (2016 population: ) is a rural municipality (RM) in the Canadian province of Saskatchewan within Census Division No. 5 and Division No. 1. It is approximately east of Regina and bisected by the Trans-Canada Highway.
The RM of Martin No. 122 incorporated as a rural municipality on January 1, 1913.
In the 2021 Census of Population conducted by Statistics Canada, the RM of Martin No. 122 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 Martin No. 122 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 following urban municipalities are surrounded by the RM.
The RM also surrounds the Ochapowace 71-26 First Nations Indian reserve.
The RM of Martin No. 122 is governed by an elected municipal council and an appointed administrator that meets on the second Wednesday of every month. The reeve of the RM is Gerald Flaman while its administrator is Cheryl Barrett. The RM's office is located in Moosomin.