The Rural Municipality of Webb No. 138 (2016 population: ) is a rural municipality (RM) in the Canadian province of Saskatchewan within Census Division No. 8 and Division No. 3. It is located in the southwest portion of the province.
The RM of Webb No. 138 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.
In the 2021 Census of Population conducted by Statistics Canada, the RM of Webb No. 138 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 Webb No. 138 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 Webb No. 138 is governed by an elected municipal council and an appointed administrator that meets on the second Thursday of every month. The reeve of the RM is Dennis Fiddler while its administrator is Raylene Packet. The RM's office is located in Webb.